Bibliothèque de recherche

Florida Tile is gaining valuable knowledge about its manufacturing process through the use of statistical tools and new computer software. At Lawrenceburg, Ky., Florida Tile has begun using a nondestructive testing method that provides valuable insight into the interaction of processing variables. The GrindoSonic testing instrument has been shown to be an accurate, easy-to-use tool, generating data that complement the statistical problem-solving methods used today.

Monolithic zirconia ceramics generally present with trade-offs between toughness, strength and hydrothermal aging-resistance, highlighting the need to develop new zirconia ceramics that are better balanced for these key properties. In this study, zirconia containing 4.5 mol% calcium-oxide stabiliser (4.5Ca-TZP) was pressed from nanoparticles and pressureless sintered at 1200–1325°C. Fully dense 4.5Ca-TZP could be obtained at 1250–1275°C with a nanometric microstructure (average grain size <100 nm) and about 20 wt% cubic-zirconia. Optimal mechanical properties were reached when sintered at 1250°C and 1275°C, combining a four-point-bending (4PB) strength of 1170 ± 140 MPa with a single-edge-V-notched-beam toughness of 9.73 ± 0.45 MPa m1/2. Furthermore, this nanometric zirconia was highly transformable, showing transformation-induced plasticity before failure with an evident deviation from linear behavior starting around 75% of the 4PB strength. Strikingly, 4.5Ca-TZP was also aging-resistant without degradation observed after 20 hours of aging at 134°C. Additionally, its translucency was similar to that of conventional 3Y-TZPs.

Ceramic pin grid arrays (PGA's) are used by microprocessor suppliers for packaging high power chips in a hermetic environment. PGA's are multilayer co-fired structures with internal metal planes and vias. The combination of materials in the packages leads to differences in thermal expansion and, therefore, stress concentrations both during the fabrication of the package and during subsequent processing with the chip in place. These stresses combined with the brittle nature of the ceramic material may lead to package cracking. The purpose of this study is to investigate a non-destructive technique to detect flaws both in incoming packages and at various stages of the assembly process. A viable method would allow increased manufacturing yield and improve reliability by detecting cracks which might eventually propagate and lead to a loss of hermeticity. It would allow testing of packages with 'live' die and would be rapid and inexpensive to be useful for testing of mass produced components. Of the nondestructive evaluation techniques available, resonant frequency testing seems to be the most rapid, least expensive, and, overall, best suited to the needs of high volume manufacturing.

Andalusite-based refractories are valued for their thermal shock resistance and volume stability. As resource scarcity and environmental concerns grow, recycled andalusite emerges as a promising alternative, though challenges remain due to impurities and variable grain decomposition of andalusite into mullite. This study examines its impact on the thermomechanical performance of shaped refractory products with varying ratios of unrecycled and recycled andalusite. Comparative X-ray diffraction analyses indicated a higher concentration of amorphous phase in the refractory composition when recycled andalusite is used, especially with more contaminated recycled grades. This increase in amorphous content correlates with a reduction in the refractoriness of the materials confirmed by refractoriness under load and impulse excitation technique measurements with lower softening temperatures for bricks containing only recycled andalusite. However, a selective approach, replacing only the coarse fraction with recycled andalusite while retaining fine unrecycled andalusite, effectively limits the concentration of amorphous phase and therefore preserves thermomechanical performance close to that of the reference material. This strategy appears promising for combining sustainability with high performance.

Aerospace propulsion systems are among the driving forces for the development of advanced ceramics with increased performance efficiency in severe operation conditions. The conducted research focused on the mechanical (Young's and shear moduli, flexural strength, hardness, and fracture toughness), thermal (thermal conductivity and coefficient of thermal expansion), and electric (dielectric properties) characterization of MgO-Al2O3, MgO-CaZrO3, and stable YSZ ceramic composites. The experimental results, considering structural and functional traits, underscore the importance of a holistic understanding of the multifunctionality of advanced ceramics to fulfill propulsion system requirements, the limits of which have not yet been fully explored.

Historically, improving refractory castables' high-temperature performance involved reducing calcium aluminate cement (CAC) content. However, even small amounts of CaO caused issues and CAC-bonded castables require careful drying to avoid damage. Cement-free castables with sol-gel binders, like colloidal silica (CS), emerged as alternatives, but CS-bonded castables still face structural stabilities at high temperatures. Given the limitations of CS-based binders, research has shifted to alternative sols like spinel and mullite. Castables bonded with them offer better high-temperature performance but suffer from extended setting times and low green strength due to lower solid content in initial sols (5-10 wt.% vs. 30 wt.% in commercial CS). In this context, spinel suspensions with 30-50 wt.% solid content were developed. Then, the impact of the solid content on setting and green mechanical properties, as well as thermomechanical properties (elastic modulus and HMOR) was analysed. The findings demonstrate that higher solid content enhances green mechanical properties of spinel-bonded castables, though demoulding time is longer than for CS-bonded castables. However, thermomechanical properties are improved notably during initial heating, surpassing those of CS-bonded castables, especially above 1000°C, where viscous or liquid phases start to form in CS-bonded materials.

This work is part of a research project aimed at producing ceramic-like materials, without the need for an initial sintering, for potential applications in catalysis or filtration at temperatures up to 1000 °C. In that context, cordierite-derived materials were prepared from recycled cordierite powder (automotive industry waste) bonded with metakaolin-potassium silicate geopolymer. The principle is that these materials, prepared at temperatures below 100 °C, acquire their final properties during the high-temperature commissioning. The focus is on the influence of the K/Al ratio and cordierite fraction on the stability of the dimensions and porosity during heating at 1000 °C, and on the final Young's modulus and coefficient of thermal expansion. Conventional and high-temperature XRD evidenced the absence of crystallization of the geopolymer binder and interaction with the cordierite filler during the heating stage when K/Al = 1 or 0.75. By contrast, crystallization of kalsilite and leucite, and diffusion of potassium ions in the structure of cordierite is evidenced for K/Al = 1.5 and 2.3. These differences strongly influence the shrinkage due to sintering and the final properties. It is shown that a K/Al ratio of 0.75 or 1 is favorable to the stability of the porosity, around 25 to 30%. Moreover, a low coefficient of thermal expansion of 4 to 4.5 × 10−6 K−1 and a Young's modulus of 40 to 45 GPa is obtained.

The developed research presents a novel experimental study of the cost-effective MgO-Al2O3, MgO-CaZrO3 perovskite, and thermally stable YSZ ceramic composites for DBD plasma actuators in aerospace applications.

This research focuses on advancing zirconia-based materials suitable for oral implant applications. The work addresses the challenge of creating ceramic compositions that demonstrate both mechanical resilience and resistance to hydrothermal aging—critical factors for long-term clinical success in the oral environment. The study investigates...

This dissertation addresses the development of ceramic materials suitable for radar frequency (RF) applications at elevated temperatures. The research explores slip casting of porous silicon nitride and pressureless liquid phase sintering as manufacturing methods to create viable radome materials. The work focuses on characterizing both mechanical and dielectric properties of porous silicon nitride structures, with the aim of producing components that can withstand high-temperature operational environments while maintaining electromagnetic transparency required for RF window applications.

γ-alumina powder was mixed with α-alumina powder to fabricate porous ceramics. With an increase in the γ-alumina content, the porosity of the ceramics first increased and then decreased. The open porosity of the ceramics was the same as their total porosity when the γ-alumina content was equal to or greater than 20 wt%. The permeability and open porosity of the porous alumina had a power-function relationship. The addition of γ-alumina not only realised pore transfixion, but also effectively enhanced the compressive strength of the ceramics. The maximum pore size of the ceramics increased with an increase in the γ-alumina content, which contributed to the increase in the bearing capacity and stiffness. When the γ-alumina content was 50 wt%, the porous alumina exhibited an open porosity of 25% and a permeability of 3.2 × 10−15 m2, while the compressive strength and elastic modulus were 325 MPa and 145 GPa, respectively. The bearing stiffness of the film with a thickness of 7.5 μm reached 13.5 N/μm at the air supply pressure of 0.3 MPa. These ceramics showed potential for application in ultra-precision aerostatic bearings.

The premise that materials permeate all aspects of our day-a-day lives is well established. The relentless pursuit for increased performance in aeronautical and aerospace industries over the last decades has provided a solid driving force for the study, research, and investigation of advanced ceramics for numerous future investments. The advanced ceramics field is believed to be an enabling technology with the potential to deliver high-value contributions for meeting both future needs and challenges. Moreover, the advanced ceramics industry is quite distinctive due to its high diversity and interdisciplinary nature that encompasses an engaging number of different processing methodologies and a variety of applications. In this sense, this dissertation project focused to perform an extensive and comprehensive literature review research, in addition to further selection, fabrication, testing, and analysis of MgO Al2O3, MgO CaZrO3, and YSZ ceramic materials which are intended to satisfy the condition of advanced multifunctional ceramic in the aeronautical and aerospace fields. Within this framework of thought, thermal protection systems, thermal barrier coatings, and dielectric barrier discharge plasma actuator applications were perceived and adopted as a jumping-off point. A step–by–step approach was adopted for the experimental procedure. More precisely, initially, ceramic composite MgO Al2O3, MgO CaZrO3, and YSZ samples were manufactured through a four stages process, i.e., material preparation, processing, sintering, and finishing. After the rectangular plates, bars, and disc specimens were obtained for the three referred compositions, the in-depth study under the microstructural, physical, mechanical, thermal, and electrical characterization followed. Ultimately, many fine ceramics are multifunctional and therefore predestined to solve the forthcoming technological and engineering challenges. It is believed that ceramics offer an enormous potential to be exploited with the knowledge of material science, i.e., through correlations between microstructural, physical, mechanical, thermal, and electrical features.

The characterization of the ceramic materials integrity without damage has become a major issue for many industrial sectors. In this context, a research study has been initiated to assess the influence of the firing conditions on mechanical strength behaviors of Porcelain stoneware and Terracottas specimens. A focus is made on a non-destructive characterization method to evaluate the residual mechanical stresses, based on the Impulse Excitation Techniques. The influence of the cooling rate (≈200 °C/min by air ventilation vs. controlled cooling at 50 °C/h) and the heating temperature (1160 °C vs. 1185 °C for Porcelain stoneware; 1100 °C vs. 1150 °C for Terracotta) have been highlighted. The effect of samples annealing at 700 °C with a heating and cooling rate of 50 °C/h was also evaluated. A significant variation of the internal friction (2.5 times less important with a controlled cooling) and a small variation of 2.0% of the Young and shear moduli of porcelain stoneware samples caused by the cooling rate variation was shown. The negative effect of the fast-cooling was also discussed on terracotta samples by a small decrease (2.7%) of the Young and shear moduli. This decrease caused by a fast-cooling is led to micro-cracks formation induced by the quartz allotropic transformation during the cooling. In the case of terracotta, the 50 °C increase of the heating temperature induces a significant increase of mechanical strength properties linked to the open porosity decrease. The internal friction calculation from Impulse Excitation Techniques are able to efficiently evaluate the heat treatment quality of a porcelain stoneware ceramic material which allows the detection of mechanical performance decrease generated by micro-cracks in ceramic products.

The characterization of the ceramic materials integrity without damage has become a major issue for many industrial sectors. In this context, a research study has been initiated to assess the influence of the firing conditions on mechanical strength behaviors of Porcelain stoneware and Terracottas specimens. A focus is made on a non-destructive characterization method to evaluate the residual mechanical stresses, based on the Impulse Excitation Techniques. The influence of the cooling rate (≈200 °C/min by air ventilation vs. controlled cooling at 50 °C/h) and the heating temperature (1160 °C vs. 1185 °C for Porcelain stoneware; 1100 °C vs. 1150 °C for Terracotta) have been highlighted. The effect of samples annealing at 700 °C with a heating and cooling rate of 50 °C/h was also evaluated. A significant variation of the internal friction (2.5 times less important with a controlled cooling) and a small variation of 2.0% of the Young and shear moduli of porcelain stoneware samples caused by the cooling rate variation was shown. The negative effect of the fast-cooling was also discussed on terracotta samples by a small decrease (2.7%) of the Young and shear moduli. This decrease caused by a fast-cooling is led to micro-cracks formation induced by the quartz allotropic transformation during the cooling. In the case of terracotta, the 50 °C increase of the heating temperature induces a significant increase of mechanical strength properties linked to the open porosity decrease. The internal friction calculation from Impulse Excitation Techniques are able to efficiently evaluate the heat treatment quality of a porcelain stoneware ceramic material which allows the detection of mechanical performance decrease generated by micro-cracks in ceramic products.

Al2O3–CaAl12O19 composites are ideal high-temperature structural ceramics, however, their poor thermal shock resistance limits their application under thermal shock conditions. In this work, ferrotitanium slag was used as the main raw material for composites preparation. Enhanced thermal shock resistance were obtained by adding 12.5 wt.% unstabilized monoclinic zirconia. A systematic analysis of the phase compositions and microstructural evolution with particular attention to crack propagation was performed. The improvement in thermal shock resistance is attributed to the enhanced crack propagation resistance. Furthermore, the enhanced crack propagation resistance is caused by multiple mechanisms, including the t-ZrO2-related stress-induced t → m phase transformation mechanism and the m-ZrO2-related microcracking mechanism. Coarsened ZrO2 particles doped with TiO2 from the ferrotitanium slag are beneficial to the occurrences of stress-induced transformation and microcracking.

Refractories are the "Backbone of Industry". Despite their great importance, refractories are frequently misunderstood, overlooked, and/or abused. The results can be extremely disruptive, costly, and even tragic. This paper defines seven main reasons for refractories problems in industry, and notes seven other contributing factors. Many practical examples are included. Based on an improved understanding of the reasons for refractories problems, as well as a thorough review of all related factors, it is possible to reduce or eliminate unnecessary and unexpected major expenses.

SiC-based kiln furniture has a maximum service temperature of 1600°C. Beyond that point, mullite-corundum materials are required. Here it is important that high hot bending strength resp. thermal fatigue in conjunction with adequate thermal shock resistance be achieved through selectively designed microstructures and appropriate raw materials.

The use of the ribbon test method in conjunction with measurement of M.O.E. by transient vibration has proved of significant assistance in the comparison of various refractory grades for thermal shock resistance and is now proving a useful tool in the development of new products. It is hoped that, once the parameters of the test are more fully understood and standardised, it will be only necessary to measure elastic modulus before and after 10 cycles or perhaps even 5 cycles will be sufficient.

Inconel 718 (IN-718) is a precipitation-strengthened nickel-based superalloy that is widely explored for its applicability in fatigue-critical applications when fabricated using additive manufacturing (AM) at an industrial scale. Among the various factors influencing its performance, the choice of shielding gas during laser powder bed fusion (L-PBF) plays a crucial yet often overlooked role in determining the material's microstructure and mechanical behaviour. This study investigates the critical influence of shielding gases like argon and nitrogen on the microstructure, defect distribution and the very high cycle fatigue (VHCF) durability of heat-treated L-PBF fabricated IN-718. Defect quantification was undertaken using a combination of optical microscopy, Archimedes density measurements, X-ray computed tomography (XCT), revealing higher defect contents in samples processed under nitrogen shielding. Microstructural analysis through scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and energy-dispersive X-ray spectroscopy (EDS) revealed pronounced variations in grain morphology and inclusion content between the two gas environments. VHCF tests were performed under fully reversed, uniaxial, stress-controlled loading at 20 kHz using dog-bone specimens with larger risk volumes to capture a conservative fatigue life assessment. Fatigue life distributions were analysed using a Weibull accelerated failure time model, revealing similar median lives but narrower scatter for argon-shielded specimens. Fractographic analysis revealed distinct crack-initiation mechanisms, microstructure driven initiation in argon-shielded specimens leaving facets at initiation sites versus defect-assisted initiation often involving inclusions along with pores and lack-of-fusion (LOF) defects in nitrogen-shielded counterparts. Although nitrogen shielding produced a refined microstructure, the elevated porosity and inclusion density-controlled crack initiation and degraded fatigue performance.

This research investigates manufacturing dense, pure copper components using filament-based material extrusion technology. Dense and pure Cu parts were manufactured using a commercially available filament with 60 vol% (93 wt%) copper. The study systematically examines how different strand deposition patterns and infill strategies influence the final properties of copper parts, employing a statistical approach to identify the factors most affecting density and mechanical performance in the manufactured components.

Engineering and design have been altered significantly by the production of metal lattice structures (MLS) utilizing additive manufacturing (AM), particularly laser powder bed fusion (LPBF). LPBF allows to produce such complex three-dimensional structures with a degree of complexity and accuracy which is not possible by conventional manufacturing, in particular regarding periodically repeated unit cells. However, despite its advantages, LPBF can cause defects, e.g. small internal porosities which in this case preferably can be observed with non-destructive inspection (NDI). Therefore, this study aims to validate the detectability of LPBF imperfections by exploring the impulse excitation technique (IET) as an NDI method for MLS and bulk samples produced by LPBF in the high-strength aluminium alloy A205 and including on-purpose manufactured defects. As a result of the measurements, the detection of selectively placed internal defects was successfully determined according to the differences in the resonant frequencies of defect-free and defected samples.

The manufacturing of dense pure Cu components by 3D micro-extrusion, a Material Extrusion (MEX) Additive Manufacturing (AM) technology, was investigated. This technology is based on the extrusion of a highly viscous powder-loaded suspension or paste at room temperature. The present study focused on the development of a complete processing route for 3D micro-extrusion from feedstock paste formulation, optimization of printing parameters, and thermal post-processing conditions. A propanol-based feedstock paste with 95 wt% Cu powder loading was prepared by employing optimized mixing and degassing steps to produce ∼98% dense Cu after pressureless sintering in pure H2 atmosphere at 1050 °C for 5 h. Printing of green parts by 3D micro-extrusion of the developed paste with optimized printing parameters followed by the same post-processing conditions enabled the fabrication of 96–99% dense Cu components with high purity. Microstructural investigation of the paste and printed parts after thermal treatment revealed the presence of residual isolated spherical pores (<10 µm) distributed within the grains, at the grain boundaries and in triple junctions. The final material has an electrical conductivity in the range 90–100 %IACS, a yield strength of 61 ± 7 MPa, an ultimate tensile strength of 194 ± 9 MPa and an elongation at fracture of 32 ± 4%.

To face the challenges raised by the qualification of metallic additively manufactured (AM) complex shaped and rough finish parts, non-destructive testing (NDT) volumetric methods are required. X-ray computed tomography (XCT) is presently the favored technique; however, alternative methods are needed to overcome the requirement of technical skills and the high cost of the technique. XCT also has limitations regarding the size and density of parts. Here, we propose an easy to use, fast, and efficient global NDT volumetric method based on resonant ultrasound spectroscopy (RUS) which basic principle relies on the comparative analysis of natural resonant frequency spectra of similar parts from the same family, both of which vibrating as free as possible. The methods have already proven to have the ability to sort parts with defects from flawless parts. In the present study, we demonstrate that RUS can also segregate metallic parts manufactured with different AM system process parameters. Eleven sets of three parts were manufactured, using a metal laser-powder bed fusion process, with different wall thicknesses, laser powers, scanning speeds, and scanning strategies. These parts were tested by RUS and then analyzed using the Z-score statistical method. The AM process parameter changes clearly influenced the resonance responses of the parts, and thus, the method is able to classify the different groups of parts according to their process parameters. Hence, the RUS methods can provide industries convenient tools to not only identify defective parts but to also configure AM machine parameters according to the expected and desired material properties.

This paper demonstrates how the impulse excitation technique (IET)—broadly established in the refractory, cement, and friction materials industries—can be adapted for quality control in additive manufacturing. The authors show how this proven testing methodology enhances defect detection and material property verification in 3D-printed components, providing AM users with a mature, reliable inspection methodology validated across industries for decades.

The current paper aims at unraveling the threefold interrelationship between process, microstructure and properties of two materials, AlSi7Mg and AlSi10Mg, processed by laser powder bed fusion (LPBF) on a 3D Systems ProX DMP 320, and subsequently heat treated under different conditions in argon atmosphere. Three thermo-physical characterization techniques were employed to monitor microstructural and concomitant mechanical property changes during heat treatment of LPBF processed Al-Si-Mg based alloys. The evolution of dissolved Si in the FCC Al matrix was monitored by electrical resistivity (ER) measurements, precipitation reactions were monitored by combining differential scanning calorimetry (DSC) with elastic property and damping measurements using the impulse excitation technique (IET). The evolution of the microstructure upon heat treatment was linked to characteristic phenomena captured by each of the three thermo-physical characterization techniques. Finally, the evolution of internal and residual stresses of both processed alloys upon heat treatment was monitored via the cantilever method.

In the context of sustainable construction, the demand for low-carbon building materials has increased interest in raw earth due to its availability and ecological benefits. Bio-based additives such as cellulose fibers and starch are often introduced to enhance mechanical and durability properties, although their impact on hygrothermal performance requires further investigation. This study examined the hygrothermal and mechanical properties of three raw earth adobe brick formulations: a reference sample, one with cellulose fibers, and one with starch. Key properties, including water vapor permeability, thermal conductivity, volumetric heat capacity, moisture buffer value, and elastic modulus, were analyzed. Notably, moisture regulation and air permeability remained excellent across all formulations, with minimal impact from the bio-based additives. These findings underscore the potential of raw earth adobe bricks, with or without bio-based additives, as a viable low-carbon material for sustainable construction.

Fire safety is a crucial issue for buildings, especially with the rise of modular construction, which demands materials that combine lightness with mechanical performance and stability. This study investigates a new concept for single-story modular constructions, made up of 3D cells assembled from thermally and acoustically pre-insulated concrete panels. These panels comprising four walls and two slabs forming the module, are stiffened, with thicknesses of only 5 cm for the walls and 7 cm for the slabs. Their constituent material is a self-compacting, high-volume steel-fiber concrete, containing 80 kg/m3 of steel fibers and 0.3 kg/m3 of polypropylene fibers. Experimental tests on a full-scale wall and slab revealed that adding 0.3 kg/m3 of polypropylene fibers effectively prevents concrete from splintering and achieves the necessary 30 min fire resistance. Standardized full-scale fire tests on walls and slabs confirmed that these thin structures meet fire resistance, insulation, and airtightness standards. The high volume of steel fibers provides ductility, maintaining structural integrity despite concrete spalling. The maximum spalling depth observed in some areas ranged 35 to 50 mm, without compromising structural performance. Overall, the modular system satisfies the fire safety requirements for structural stability (no collapse) and performance in single-story modular construction.

This study investigates the impact of incorporating construction and demolition waste (CDW) aggregates and Alfa natural fibers on the performance characteristics of asphalt mixtures, with a focus on mixing temperature. Several formulations were developed and evaluated through multiphysics property measurements, including density, ultrasonic pulse velocity, rutting resistance, thermal conductivity, and spectral reflectance. The results indicate that Alfa fibers enhance thermal resistance and spectral reflectance. Notably, incorporating 1% Alfa fiber and 20% CDW while reducing the mixing temperature to 150 °C significantly improves rutting resistance. These combined effects result in an optimized formulation that is more resistant to thermal stress during service, thereby enhancing its performance at elevated temperatures. These findings highlight the potential of integrating CDW and natural fibers into asphalt mixtures to develop environmentally friendly and thermally resilient materials, particularly for warming climate regions.

Finding eco-friendly products that are beneficial to the environment and serve as tools for sustainable development is a contemporary challenge. This work illustrates the recovery of bio-waste-based materials, which not only improve the hygrothermal properties of gypsum but also promote the paper and wood recycling processes in a circular economy approach. The samples were subjected to tests for density, water absorption, ultrasonic pulse velocity, flexural strength, compressive strength, and thermophysical property characterization. A statistical analysis of variance was used to study the impact of waste on the physico-mechanical behavior of gypsum, leading to the development of predictive models that can be used to predict and optimize the performance of bio-composites in various applications.

The Grindosonic apparatus, new equipment capable of indirectly determining rock compressive strength, is discussed. This utilizes the principle that elasticity theory can be applied to rock masses and directly measures the fundamental vibration frequency of a rock sample of regular dimensions following shock excitation. Dynamic Young's modulus and a variety of other parameters can be established. Samples of Upper Cretaceous Chalk and Upper Jurassic Portland Limestone are used to demonstrate the apparatus and its application. Test specimens were prepared and analysis conducted on material extracted at a number of locations throughout the Isle of Purbeck in Dorset, UK. Samples suitable for deformation in triaxial compression were also prepared and correlations drawn between compressive strength, dynamic Young's modulus, porosity and density.

The high mechanical resistance of metallic glasses makes them innovative substitutes for conventional crystalline metals in mechanical and micromechanical applications, but their durability in real system remains difficult to evaluate. Historically, the hardness has been regarded as the most crucial parameter in predicting the wear and the scratch resistance of materials. Metallic glasses are no exception to this convenient but too imprecise rule. It is now generally admitted that additional mechanical parameters, reflecting the structural state, must be taken into account to predict more accurately the robustness of metallic glasses. Using the bonded interface technic, indentation and scratch tests were conducted on a Cu47Zr46Al7 (at%) metallic glass to evaluate the role of the specific plastic deformation mechanisms of metallic glasses during the formation of a scratch groove. The analysis of shear banding activity below and along the scratch helps to explain the observed morphology of the shear bands and the consequence of associated strain softening on the scratch depth is highlighted. The length of the shear bands below the scratch groove is found to be correlated with the scratch resistance as well as with the length of the shear bands observed on the surface. This offers a useful surface indicator to evaluate scratch resistance without the use of the challenging bonded interface technique for future studies.

Iron‑silicon (FeSi) electrical steel is a key soft magnetic material for electric machine cores. Increasing the silicon content above 3.5 wt% enhances magnetic performance by improving resistivity and eliminating magnetostriction. However, the brittleness of high-Si alloys limits the use of conventional processing methods. Additionally, the growing demand for complex, high-performance motor designs highlights the need for alternative fabrication methods, such as Additive Manufacturing. This study investigates the manufacturing and characterisation of monolithic Fe-6.5 wt% Si parts produced via filament-based Material Extrusion (MEX) followed by pressureless sintering. A tailored filament was specifically developed for this work, incorporating high-Si steel powder (6.5 wt% Si) to enable extrusion-based processing of this composition. The sintered parts exhibited a relative density of 96–99 % of their theoretical density and demonstrated a reduction of C, O, N and H content in the bulk upon densification. A flexural strength of 855 ± 96 MPa was measured on 4-point bending bars, revealing brittle fracture behaviour. EBSD analysis of the cross-section did not reveal a strong crystallographic texture, and the average grain size was measured to be 394 μm. The magnetic properties of stacked 0.35 mm thin rings exhibited lower core losses than NO20 at 100 Hz, a remarkable result considering that, despite the inherent advantages of the Fe-6.5%Si composition, standard laminations were outperformed for the first time. Finally, two stator core designs were fabricated as a demonstration of the versatility of the technology to build complex parts.

This research examines how grinding operations affect the characteristics of API 5L X70 high-strength low-alloy pipeline steel. The study involved experimental grinding tests where temperatures were measured using an innovative method. The investigation specifically focused on rubber bonded elastic wheels used in the grinding process and...

An object's modulus of elasticity is a function of its properties. These properties depend on the manufacturing process. Several methods exist to determine the modulus of elasticity: Stress-deformation curve; Ultrasonic testing; Sonic testing. When working with a stress-deformation curve the deformation of refractory material is slight, thus measurements are imprecise and small. Ultrasonic and sonic testing methods are much easier to perform. For complex shaped objects, the sonic method better determines properties and imperfections because it involves the total volume of the object. Being directional, the ultrasonic method requires several measurements per object. The sonic testing method has been used for years to: Detect the appearance of cracks as a result of thermal shock; Study property variations of a lot as a function of resonant frequency; Test and sort parts where guaranteed performance is required. Resonant frequency measurements were performed at the European company, Sacilor-Sollac Steelworks Products Test Laboratory, using GrindoSonic equipment on loan from the Minerals & Refractories Laboratory, Nancy, France. Tests were done on different lots of ladle brick to determine the feasibility of the sonic testing method, and to pinpoint correlations between physical properties and the modulus of elasticity.

The accuracy and advantages of the non-destructive resonant frequency technique (impulse excitation technique) for the final inspection of conventional refractory products are discussed. Mathematical models and correlations for alumina brands are presented.

Hexagonal boron nitride (BN) is the material of choice for manufacturing break rings for the horizontal continuous casting of steel. Due to the criticality of this application, only a 100% acceptance level can be tolerated. A non-destructive testing method was successfully developed to accomplish this. Comparison of this method with more traditional non-destructive tests showed it to be comparable.

The relation between the manufacturing conditions and the resulting properties of grinding wheel was studied using the vitrified bonded grinding wheels with white fused alumina abrasive grains as a model. The manufacturing conditions studied included molding pressure, bond content and firing time. The properties studied were bending strength, Young's modulus and apparent density. The wheel properties were affected markedly by the manufacturing conditions. The results were explained through the microstructural consideration. An uniform green density after pressing was required for making a reliable grinding wheel with uniform quality.

A series of experiments were performed to evaluate the Grindo Sonic Method which purported to measure the elastic modulus of a wheel non-destructively. The modulus measurements showed that identically labelled wheels might have very different modulus readings. Grinding tests using these wheels indicated that the grinding performance in terms of wheel wear could be correlated successfully with the elastic modulus.

A bonded abrasive is composed of abrasive grains and bonding material. As it is mostly used in a shape of a disk, the name 'grinding wheel' has been used in a broad sense inclusive of a grinding stick. Grade or hardness is one of the most important characteristics of a grinding wheel, because it is closely related to the grinding performance at work. Although numerous methods for testing grade of a grinding wheel have been in use up to now, a conclusive method has not yet been agreed upon to the satisfaction of all. Most grinding wheel manufacturers employ their own mechanical graders such as scratching and sand-blasting testers. In recent years the sonic method has gradually been in use, because the measuring procedure is handy and non-destructive, and the measured value has a real physical significance.

This research presents a non-destructive industrial protocol for the mechanical characterization and classification of tree trunks intended for use as structural beams and floors. The protocol enables proof-loading assessment without damaging the timber, making it suitable for production-line quality control in sawmill operations.

This thesis focuses on non-destructive characterization of mechanical properties of entire wood logs using the GrindoSonic device. The research explores the use of GrindoSonic for characterization purposes of log stiffness, investigating how this non-destructive testing method can effectively assess the structural properties of timber without...

This German patent describes a mechanical device for strength-based sorting of sawn timber that combines two measurement stations. The first station uses single excitation of wood through impact to measure longitudinal vibrations and calculate oscillation time. The second station employs X-ray radiation to determine bulk density and knot characteristics across the wood's width and length. The system calculates the mean dynamic modulus of elasticity by integrating oscillation time data with density measurements and dimensions. A computer evaluation device then assigns appropriate sorting classes, enabling optimal utilization of the timber resource through comprehensive material analysis.

Over the years and up to November 19th, 1979, problems have been encountered on the honing of cylinder liners. We have had glazing of bores, retraction glazing marks and time cycles dragging out from one minute to five minutes, this meant the hone was a constraint in the line and production stood at 270 liners per shift. During this period we also encountered sizing problems associated with glazed bores, and roundness, due to higher honing pressures which had to be used, and due to the higher pressures there was a high mortality rate on the work-holding rubber bushes used in the hydraulic fixtures. When glazing and problems with bore texture occurred, honing stones could be changed any time within their life span so we suffered a fairly high rejection rate and wastage, sometimes hones lasted only half an hour. Both the abrasive company and the machine tool company engineers have been to Darlington many times over the years at high cost to Cummins, but have never solved the problem on any permanent basis.

By using stones of similar bond hardness for each honing operation on diesel engine parts, Cummins has improved the component's surface finish, reduced stone consumption considerably, and cut overall manufacturing costs. The savings are achieved with a device which tests and classifies the stones non-destructively before use.

Fiber hybridization is suggested to enhance the properties of fiber-reinforced composites. Regarding the matrix, thermoplastic alternatives to conventional thermosets are needed to balance mechanical performance and sustainability. We combined woven flax and carbon fibers with a polyamide 11 matrix into a hybrid biocomposite and studied its manufacturing process as well as its impact, tensile, and damping properties. Mechanical damage was investigated using scanning electron microscopy and X-ray computed tomography. Hybridization significantly improved the tensile properties: 233% higher modulus and 432% higher strength than pure flax composites and 19% higher failure strain than pure carbon composites. Additionally, the hybrid composites exhibited a positive hybrid effect with respect to the impact resistance, characterized by higher displacement at maximum impact force and occurrence of combined damage mechanisms. Although the damping behavior of the hybrid composites remained inferior to that of pure flax composites, their damping factor was 20% higher than that of pure carbon composites. These results provide valuable insights into the mechanical performance of carbon-flax hybrid composites.

The mechanical properties of a gray cast iron disc brake rotor are directly influenced by the amount and morphology of the graphite present throughout the rotor. Two of these properties, the modulus of elasticity and the damping capacity, can have a significant effect on the propensity for the disc brake rotor to produce noise. The noise propensity of a disc brake is in a large part determined by the relationship between the rotor resonances and the resonances of the other brake components such as the pads. In this paper, we are concerned only with the effect that modulus of elasticity has on disc brake noise through its influence on rotor resonances. The amount and morphology of the graphite in gray cast iron is determined by the carbon content and silicon content of the iron. The carbon and silicon content are measured by one parameter called the carbon equivalent. For gray cast iron the relationship between carbon equivalent and modulus of elasticity is almost linear for the grades used in disc brake rotors. This relationship allows the modulus of elasticity and, in turn, the rotor resonances and resulting brake noise to be influenced by the carbon equivalent of the rotor. A case study showing the effectiveness of controlling rotor resonances through carbon equivalent to reduce brake noise is presented. The subsequent effect of foundry process control on brake noise propensity is also evaluated.