Shock Test Research Articles

High-temperature mechanical properties and thermal shock resistance of an alumina-fiber-reinforced alumina ceramic matrix composite

An alumina-fiber-reinforced alumina ceramic matrix (Al2O3/Al2O3) composite is fabricated by a slurry infiltration process in this study. The slurry contains Al2O3 powders with broad particle size distribution (d10=0.35 μm, d50=0.57 μm, d90=1.90 μm). The resultant Al2O3/Al2O3 composite exhibits a density of 2.95 ± 0.02 g/cm3 and porosity of 25 ± 1%. Mechanical properties are assessed via three-point flexural tests, revealing a high flexural strength of 400 ± 8 MPa at room temperature. The high-temperature mechanical properties and thermal shock resistance are further examined. The flexural strength remains stable from room temperature to 1100°C, while temperatures up to 1200°C induces superplastic behavior. After thermal shock tests (5, 10 and 20 cycles at 1100°C), the composite maintains a stable microstructure and flexural strength. The Al2O3 powders with broad particle size distribution are beneficial to the high-temperature mechanical properties and thermal shock resistance of the Al2O3/Al2O3 composite.

Thermal Shock Damage and Failure Mechanism of 2D Laminated SiC/SiC with Barium‐Strontium Aluminosilicate‐Based Environmental Barrier Coating

Thermal shock damage is a key issue for the stable service of SiC/SiC with environmental barrier coating (EBC) in aero‐engines. The thermal shock damage behavior of SiC/SiC with barium‐strontium aluminosilicate (BSAS)‐based EBC in an air atmosphere quenched by air and water media between RT and 1200 °C is systematically investigated. After 600 thermal shock cycles, cracks form in the EBC due to a sharp increase in the internal thermal stresses, and a SiO2 TGO layer is formed on the Si bonding coat. Based on the TGO thickness, damage within BSAS/mullite coatings is quantified by the oxygen permeability (2.541 × 10−11 mol·(atm cm s)−1), which is increased by 2.5 times compared to static oxidation. Despite cracking damage occurring in the SiC matrix of SiC/SiC substrates, the load‐bearing capability of SiC fibers is improved due to the modulus matching of the fiber/matrix. Oxidation damage is dominated the degradation of the performance of SiC/SiC substrates, whose flexural strength is decreased by 15% after 600 cycles. In the thermal shock test quenched by water media, the strength retention of SiC/SiC‐EBC is below 60%, and an increase in internal defects and even delamination of the SiC/SiC substrate are the main reasons for the thermal shock failure of SiC/SiC‐EBC.

Effect of aged treatment on improving the performance of HVAF WC–Cr3C2–Ni coating on crystallization roller

The thermal shock resistance and high-temperature performance of WC–Cr3C2–Ni coatings on the surface of the crystallization roll after aged treatment were investigated in this study. The aging treatment at 320 ℃ for 2.5 h facilitated the diffusion of Cu element from the C17200 beryllium copper substrate toward the coating side of WC–Cr3C2–Ni coating, thereby enhancing the bonding between the coatings and substrates. After the aged treatment, the internal structure of the C17200 substrate changed from a dendritic structure to an equiaxed crystal structure, the hardness increased from 225.71 Hv0.5 to 406.52 Hv0.5 (80.4 % increased), and the wear resistance increased.Although the aging treatment reduced the hardness of the coating slightly (from 1257.58 Hv0.5 to 1155.16 Hv0.5, a decrease of 8.1%) and wear resistance (the coefficient of friction, from 0.335 to 0.312, a decrease of 6.9%). However, in the thermal shock test, the thermal shock resistance of the coating after aging treatment was increased from 19 times to 20 times (5.3% increased). However, the thermal shock failure cracks between the coatings and the substrates were transferred from the substrate part to the joint part of the two, which effectively avoided the waste of the crystallization roller substrate in the maintenance process. This research effectively reduces the purchase and maintenance costs of steel mills in actual production and provides theoretical support for cost reduction and efficiency increase in other HVAF (high-velocity air fuel) coating applications.

Effects of Thermal Shock from Coastal Nuclear Power Plant Discharges on the Survival of Four Fish Species Under Variable Temperature Rise

In this study, we simulated water temperature changes under variable frequency temperature rise conditions caused by coastal nuclear power plant discharges and conducted thermal shock tests on four fish species: Trachinotus ovatus, Nibea albiflora, Larimichthys crocea, and Acanthopagrus schlegelii at acclimated water temperatures of 25.0°C and 27.5°C during the summer. The effects of these temperature variations on the thermal shock response of the four fish species were analyzed. The results indicated that at 25.0°C, the mortality rate of N. albiflora exhibited an overall upward trend with increasing temperature and duration frequency, with an average mortality rate ranging from 10±3.3% to 38.9±3.3%. For L. crocea, mortality was observed only in the 8.5ºC-100% duration probability group, while other groups had a 0% mortality rate. At 27.5°C, A. schlegelii showed an average mortality rate of 10±3.3% at an 8.5ºC-100% duration probability, with all other groups showing 100% survival. The average mortality rate of T. ovatus at 8.5ºC-100% was 6.7±3.3%, with no mortality in the other treatment groups. The expression level of the hsp70 gene in the liver of N. albiflora increased with higher temperature rise amplitudes and longer frequency conversion durations. Similarly, the hsp70 gene expression in L. crocea and A. schlegelii increased with rising temperatures, though there were no significant differences among groups with varying frequency conversion times. In contrast, the hsp70 gene expression in T. ovatus remained relatively stable across temperature rise treatments, showing no significant differences with varying frequency conversion durations. The heat stress tolerance ranking among the four fish species was determined to be L. crocea > N. albiflora > T. ovatus > A. schlegelii.

The Cr/Cr2N multilayer coating with high load-bearing capacity and thermal shock resistance

By utilizing the multi-arc ion plating (MAIP) technique, multilayer coatings with varying Cr/Cr2N ratios and uniform thicknesses were deposited onto a nitrided Cr–Ni–Mo–V steel substrate. The evolution of microstructure and mechanical properties was characterized using scanning electron microscopy, X-ray diffraction, and micro-Vickers hardness testing. The load-bearing capacity of the multilayer coatings with varying modulation ratios was comprehensively evaluated through Vickers indentation tests with a 10-kgf load, Rockwell hardness testing with a 150-kgf load, and scratch tests with loads of 60 and 100 N. The coating with a Cr/Cr2N layer modulation ratio of 0.2/0.4 μm exhibited a hardness of 1385 HV and an adhesion strength of 91 N. Under a 10 kgf load, this coating also demonstrated excellent fracture toughness, and did not exhibit any radial cracks in the Vickers indentation. Subsequently, a thermal shock test, involving quenching from 900°C water to 25°C, was conducted on the coating with the best comprehensive performance. The multilayer coating with high load-bearing capacity could withstand 52 thermal shock cycles before delamination occurred. Failure analysis further confirmed that the multilayer coating with enhanced load-bearing capacity effectively resisted thermal shock.

Synthesis, microstructure and physical properties of aluminium titanate ceramics modified by multiple additives

Aluminium Titanate (Al2TiO5, AT) ceramics are renowned for their excellent thermal shock resistance, which is crucial in aerospace, automotive, and metallurgical applications. Despite their widespread use, AT ceramics have inherent flaws, including thermal expansion anisotropy and decomposition within a specific temperature range. This study synthesized AT ceramics from bauxite clinker and anatase via solid-state reaction with varied additive concentrations, aiming to examine mechanical strength and microstructural enhancements of AT ceramics. Y2O3 and aluminium powder (Al powder) positively affected mechanical strength and sintering densification, while SnO2 negatively affected densification and AT synthesis. The fabricated composite additive AT ceramics exhibited compressive strength of 190.5 MPa, with a stable 58 % strength retention rate after thermal shock testing, indicating good thermal shock resistance. This study demonstrates composite additives' effectiveness in improving thermal shock resistance and mechanical strength, offering insights for enhancing AT ceramics' performance in industrial applications.

Research on the ultra-high acceleration method based on dual-mass shock amplifier

Abstract Spacecraft are exposed to rigorous mechanical conditions throughout the launch, explosive decoupling, and landing stages. Electronic devices intended for space deployment are required to endure shock-induced reliability assessments. This study delves into the composition and operational principles of a high-g shock testing system. Furthermore, the paper derives a collision kinematics model from established classical collision dynamics and constructs analytical frameworks for both a single-degree-of-freedom and a two-degree-of-freedom spring-mass systems. Additionally, it investigates the principles of acceleration amplification. The finite element analysis model was computed, and its simulation outcomes were compared and contrasted with the data from shock experiments. The findings indicate that the finite element model is capable of accurately capturing the peak acceleration for both the drop table and DMSA table, with a discrepancy of no more than 5%. The acceleration of the amplifier is enhanced by approximately 40 times following the momentum exchange during the second collision. Moreover, the shock system, equipped with a dual mass shock amplifier (DMSA), is capable of producing accelerations exceeding 30,000G.

Numerical study on flow and heat transfer of combustion chamber and turbine under thermal shock test

In order to more accurately analyze the influence of the interaction between the aero-engine combustion chamber and the turbine, this paper establishes a combustion chamber-turbine cross-component model based on a high-pressure first-stage guide vane thermal shock test device for numerical research. The SST k-ω turbulence model, non-premixed combustion model and P1 radiation model are selected, and the test conditions are used as boundary conditions to carry out fluid-solid coupling unsteady calculation in ANSYS FLUENT. The numerical results are in good agreement with the experimental results. The complex flow field information between the combustion chamber and the turbine is obtained by analyzing the numerical results. It is found that there is an interaction between the combustion chamber and the turbine. The results show that the hot spot at the outlet of the combustion chamber will cause a stronger thermal shock to the downstream of the high-pressure first-stage guide vane during the migration process. The influence of the high-pressure first-stage guide vane on its upstream can be traced back to the position 0.3 times the chord length from the outlet of the combustion chamber.

Phase transition heat storage and self-healing mechanism of spinel-calcium aluminate composite aggregate in corundum castable

Corundum-spinel castable is a vital refractory material used in steel ladle linings. Conventional approaches for assessing the thermal shock resistance of corundum-spinel refractory are not entirely representative of the actual application scenarios. This study investigates the influence of spinel-calcium aluminate composite aggregate on the thermal shock resistance of corundum castable using supersonic frequency induction heating technology. The research uncovers how CMA aggregate enhances the thermal shock resistance of corundum castable by cyclic thermal shock tests under varying operational conditions. Results reveal that the incorporation of CMA aggregate led to significant improvements in cold crushing strength and strength retention ratio following thermal shocks. The observed enhancement predominantly stems from the presence of CA/CA2 phase within the CMA aggregate, which undergoes a solid-liquid phase transition at high temperatures, enabling the absorption and retention of substantial heat and aiding in the repair of microcracks within the materials and at the interfacial regions.

Behavior of Polymeric Substrates and Sintered Silver Printed Hybrid Electronic Assemblies Subject to Extreme Acceleration Levels and Elevated Temperatures

Abstract This paper focuses on the response of printed hybrid electronic (PHE) assemblies with polymeric substrates and additively manufactured sintered silver electrical traces subject to extreme mechanical shocks (up to 100,000 g) and high temperatures (up to 150 °C). The substrates are hemispherical domes of injection-molded polycarbonate and polysulfone thermoplastics. Trace deposition onto the domes is accomplished by a novel process that combines conventional milling with extrusion printing to recess silver traces and dielectric insulation within the surface of the substrate. Mechanical shock testing is performed using an accelerated-fall drop tower equipped with a dual mass shock amplifier (DMSA) able to generate accelerations from 10,000 g up to 100,000 g with pulse durations of ∼0.05–0.1 ms and impact velocities of 6.5–20.5 m/s. Specimen performance is characterized by electrical and physical testing before and after testing. While polycarbonate domes survive multiple drops at all acceleration levels and temperatures, they are sensitive to heat and susceptible to warping and structural deformation at 150 °C which can compromise trace performance. Polysulfone domes can survive these temperatures without issue, but are less shock resistant and only survive 3–4 drops at 100,000 g (compared to 30+ for polycarbonate domes). Trace resistance is used as a metric to assess trace performance. All traces exhibit progressive long-term degradation over the course of multiple shocks, followed by instantaneous discontinuity during the final shock event. Trace failure (defined as the doubling of static trace resistance) occurs at ∼105–106 J/kg cumulative impact energy for all acceleration levels.

Effect of Different Tempering Media on Fracture Toughness and Mechanical Properties of Carbon Steel

In this study, the effect of different thermal carbons on the impact resistance of heavy carbon, which contains 0.4% of. The focus was on how the resulting biochemistry affects the microstructure of the steel, and thus its mechanical properties. Steps: Impact test before heat treatment: Charpy impact test was performed on pre- impact specimens before any specimen was made. This test helps to determine the original impact of the steel without any modification in its microstructure. Tempering procedure: After that, it was further investigated by exposing it to high temperatures and then cooling it rapidly. This method is for market formation, which is a must. It was retested after tempering. The results showed a significant increase in the shock cases after tempering due to the formation of the texture which increased the strength of the specimen. Flame tempering (surface heat treatment): In this type of treatment, only the surface is heated with a flame and cooled rapidly, which results in the formation of a strong martensite texture on the surface, while the core of the specimen remains softer. When tested, it did get shock, but the amount of increase that occurred with full shock was not reduced. The reason for this is that the hardening in God is only on the surface while the core of the eye remains flexible, which leads to a reduction in contrast. Carburizing (surface heat treatment): Carburizing treatment is performed on some samples, which is a method that involves adding carbon to the outer surface of the fulminate and cooling it rapidly, resulting in a solid, hard material. When performing the shock test, it did get a shock that improved, but a case like flame hardening, you did not have very many shocks in full hardening.

The Effect of Shot Blasting Abrasive Particles on the Microstructure of Thermal Barrier Coatings Containing Ni-Based Superalloy

Grit particles remaining on the substrate surface after grit blasting are generally considered to impair the thermal performance of thermal barrier coatings (TBCs). However, the specific mechanisms by which these particles degrade the multilayer structure of TBCs during thermal cycling have not yet been fully elucidated. In this study, the superalloy substrate was grit-blasted using various processing parameters, followed by the deposition of thermal barrier coatings (TBCs) consisting of a metallic bond coat (BC) and a ceramic top coat (TC). After thermal shock tests, local thinning or discontinuities in the thermally grown oxide (TGO) layer were observed in TBCs where large grit particles were embedded at the BC/substrate interface. Moreover, cracks originated at the concave positions of the TGO layer and propagated vertically towards BC; these cracks may be associated with additional stress imposed by the foreign grit particles during thermal cycling. At the BC/substrate interface, crack origins were observed in the vicinity of large grit particles (~50 μm).

Experimental study under thermal shock environment to investigate effect of welding width on properties of ultrasonically welded joints of multiple copper cables

Based on the ultrasonic welding technology, this study uses three different welding widths to weld copper cables with different specifications. The influence of welding width on the mechanical properties and microstructure of each group of welded joints was systematically studied for the first time. The thermal shock test was carried out for each group of welded joints under optimum welding width to simulate the influence of severe temperature change environment on joint performance. It is found that the cross-sectional area of joint is 20 mm2 and optimal welding width of joint composed of two and three cables is 7 mm. The optimal welding temperature of the joint composed of four cables is 5 mm. Under the optimal welding width, the average shear strength of two-cable joint reaches 309.4 N. The four-cable joint is only 232.2 N. Moreover, the welding strength weakens significantly as the number of cables and the peak temperature decreases. The high temperature of bonding interface is the key factor to form a good weld. The peak temperature during welding is negatively correlated with the porosity of joint and positively correlated with peeling strength of joint. In addition, the morphology of ultrasonically welded joints has changed obviously after thermal shock test. With the participation of oxygen, the surface of welded joint is gray and bright brass, while the interior of joint is purple due to lack of oxygen. Moreover, the phenomenon of atomic diffusion and thermal expansion generates joints which were initially in a mechanically interlocked form and welding interface of the metallurgical bond under the action of high temperature. So the maximum joint peel strength is slightly improved.

Effect of filer content on the thermal characteristics of underfill materials for Ball-Grid-Array component package

High-density integration and fast processing speed in the semiconductor industry have increased heat generation in electronic devices. Underfill materials, known for their high thermal conductivity and low coefficient of thermal expansion (CTE), offer a potential solution to dissipate heat and improve device reliability. In this study, we investigate the effect of filler content on the thermal reliability of underfill materials for ball grid array (BGA) component packaging. Mainly, we investigate the thermal conductivity, CTE, and mechanical properties of different filler contents of Al2O3 and Al2O3–BN hybrid underfills to facilitate heat dissipation and improve device reliability. The thermal conductivity of the underfill materials was evaluated by measuring the surface temperatures of underfill molded flip-chip light-emitting diodes (FCLEDs). The mechanical properties and thermo-mechanical reliability of the underfill materials were evaluated via a three-point bending test of the underfill packaged BGA components after the thermal shock test. The results showed that optimizing underfill properties based on specific application environments is crucial for obtaining enhanced thermal reliability and mechanical properties of underfill packaged BGA components.

Novel anti-oxidation coating prepared by polymer-derived ceramic for harsh environments up to 1200 °C

Environmental barrier coatings (EBCs) are protective barriers that could prevent internal materials from oxygen and harmful agents. However, the combination between EBCs and polymer-derived ceramics (PDCs) is relatively hard but essential. In this work, an anti-oxidation coating based on PDCs is fabricated on target SiBCN ceramics by spraying. The coating reveals a uniform and continuous structure with an approximate thickness of 11.7 μm. Experiments and characterization such as oxidation, thermal shock, scratch, and electrical resistance tests were carried out to investigate the performance of coating. The results show that during the high-temperature oxidation process, the coating surface undergoes a molten phase transformation that effectively seals pores and cracks, preventing oxygen diffusion into the ceramic interior. Moreover, the coating can withstand 20 thermal shocks without failure, and firmly adheres to the substrate even after prolonged oxidation and repeated thermal cycling. Comparative analysis of temperature-resistance results demonstrates the efficacy of the coatings in protecting against oxidation up to 1200 °C. The developed PDC-EBCs here exhibit remarkable resistance to oxidation and thermal shock, along with high insulation resistivity. This strategy offers a straightforward and efficient solution for protecting electronic materials in harsh environments.

Influence of ZrSiO4-SiC reinforcement on the decarburization and thermal shock behavior of MgO-C refractories

The slag corrosion resistance and thermal shock and of MgO-C refractories are crucial in the steelmaking industry. The current study presents a novel approach to enhance these properties by incorporating reinforcing particles such as zircon and silicon carbide. MgO-C refractories containing various amounts of ZrSiO4 and SiC were prepared and subjected to slag corrosion and thermal shock tests. X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were used to characterize the microstructure and chemical composition of the samples. The findings demonstrated significant improvements in the overall performance of the refractories with the addition of zircon and silicon carbide. Thermal shock resistance increased from 11 cycles for MgO to 18 and 15 cycles due to the increased fracture toughness and altering crack propagation paths with the addition of ZrSiO4 and SiC particles. The formation of a CaZrO3 phase within pores significantly improved slag corrosion resistance. This led to a reduced slag penetration depth and a thinner decarburized layer compared to the unreinforced MgO-C refractory. SiC decomposition formed a protective silica layer, while zircon particles locked MgO grain boundaries, further enhancing corrosion resistance. The study proposes a corrosion mechanism based on the formation of microstructure containing dense and decarburized layers. These findings highlight the potential of reinforcing particles to improve the performance of MgO-C refractories in steelmaking applications.

Crack behaviour and failure mechanisms of air plasma sprayed (Gd, Yb) doped YSZ thermal barrier coatings under oxy-acetylene flame thermal shock

This paper examines the performance and failure mechanisms of atmospheric plasma sprayed (Gd, Yb)-doped YSZ (RYSZ) thermal barrier coatings (TBCs) under oxy-acetylene flame thermal shock conditions. The study involved cyclic thermal shock testing at temperatures of 1400 °C, 1500 °C, and 1600 °C for 10-min intervals until failure occurred, with failure counts recorded as 6, 2, and 2, respectively. During the thermal shock tests, tensile stress in the top coat (TC) caused vertical cracks. The growth of the thermally grown oxide (TGO) layer concentrated stress at the top coat/bond coat interface, leading to transverse interfacial cracks. As the shock temperature increased, the density of vertical cracks and the length of transverse interfacial cracks also increased. Additionally, transverse cracks developed in the TC due to sintering of the surface region at higher shock temperatures. The interaction between vertical and transverse cracks was critical to the spalling of the TC. Variations in crack densities and lengths resulted in different failure modes of the TBCs, depending on the thermal shock temperatures (1400 °C, 1500 °C, and 1600 °C).

Novel high-entropy (La0.35Gd0.35Y0.35Sm0.35Yb0.6)Zr2O7 thermal barrier coatings: Thermal cycling performance and failure behavior

The high-entropy ceramic (HEC) (La0.35Gd0.35Y0.35Sm0.35Yb0.6)Zr2O7 has emerged as a strong candidate for thermal barrier coatings (TBCs) due to its exceptional thermal properties. We investigated the thermal shock resistance of HEC–lanthanum zirconate (LZ)/yttria partially stabilized zirconia (YSZ) (i.e., the HEC coating) and LZ/YSZ (i.e., the LZ coating) double-ceramic-layer TBCs fabricated via plasma spraying. During thermal shock testing at 1100 °C, the LZ coating failed after 60 ± 3 cycles, while the HEC coating had a considerably longer thermal cycling lifetime of 135 ± 5 cycles. The HEC coating's superior performance is attributable to its enhanced oxygen barrier properties and inherent lattice disorder; the former reduced the growth rate of the thermally grown oxide, and the latter increased lattice defects and distortion. These factors helped improve the thermal expansion coefficient and reduced interlayer thermal stress accumulation. Furthermore, the higher fracture toughness of the HEC layer impeded crack propagation, collectively enhancing the TBCs' thermomechanical shock resistance. These findings underscore the potential of (La0.35Gd0.35Y0.35Sm0.35Yb0.6)Zr2O7 as a robust material for extending the service life of TBCs in high-temperature environments.

Crimp Height influence over Resistivity in Wiring Crimping Process

Abstract The main purpose of this paper is to present the influence between the crimp height and the resistivity for a crimp joint between a copper contact and a wire copper stranded cable using statistical relevant analysis. The experiment followed the analysis of 45 crimped assemblies grouped in 3 main categories to simulate a potential validation procedure according to the international validation process requirements from: DIN (“Deutsches Institut fu r Normung”) with the corresponding Romanian standard SR EN 60352-2:2006 and SAE/USCAR-21 REVISION 3. The baseline used was the behaviour of the resistivity versus the pre-set crimp height of the crimped joints before and after thermal shock test to enable us to conclude if we have a significant relation between the crimp height of the assembly joint and the resistivity.

Solid face sheets enable lattice metamaterials to withstand high-amplitude impulsive loading without yielding

Owing to their ability to provide tunable mechanical responses, lattice materials are frequently studied to elucidate their response to static and dynamic loads. However, these roles are typically in opposition: static loads must be supported sufficiently far away from the onset of buckling or yielding, whereas dynamic loads are typically ameliorated by crushing of the lattice, which provides excellent energy-absorption due to the large plastic deformation accompanying densification. In contrast, this work considers the octet truss as an exemplar topology, in a structural role where it must simultaneously support static loads while enduring high-amplitude impulsive loads. This study focuses on the ability to withstand impulsive loads without yielding, an essential prerequisite to enduring dual loading. Computational studies using the ALE3D hydrocode were performed to examine the response of the octet truss under a short temporal width impulse shape associated with laser-driven shocks. A key finding was that covering the lattice with a solid face sheet and treating this face sheet thickness as a design variable allows the Taylor-like pulse to be attenuated prior to entering the weaker lattice, at the cost of added mass up front. Experimental validation was accomplished by laser-driven shock testing, using octet trusses printed out of Ti-5Al-5V-5Mo-3Cr. The results show that for a given quantity of mass, the attenuation is maximized when as much mass as possible is moved into the face sheet, leaving a more slender lattice structure. The effect of placing mass in the face sheet rather than lattice beams dominates the effect of relative density, to the point where a low-mass structure with most of the mass concentrated in the face sheet can outperform a high-mass structure with most of the mass in the lattice. By further understanding the propagation of short pulse width waves within under-dense structures, this study expand the domain of applicability of such structures, including lattice materials, to challenging dual-loading regimes spanning decades of strain rates.