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Aiming at optimizing properties of alumina-spinel refractory castables, coarse corundum particles were replaced partially with the particles of a novel porous multi-component CMA (CaO-MgO-Al2O3) aggregate in the same size. Properties including the bulk density, apparent porosity, strength, slag corrosion resistance, thermal shock resistance and thermal fatigue resistance of alumina-spinel refractory castables containing CMA aggregates were evaluated contrastively. The results demonstrated that the incorporation of CMA aggregates can significantly improve thermal shock resistance and thermal fatigue resistance of castables, although companying with slight decrease in the bulk density and strength. Moreover, slag penetration resistance of castables can also be enhanced by CMA aggregates with appropriate particle size. The influence of CMA aggregates on properties of alumina-spinel refractory castables depended strongly on their particle size.

Refractory materials are an important pillar for the stable development of the high-temperature industry. A large amount of waste refractories needs to be further disposed of every year, so it is of great significance to carry out research on the recycling of used refractories. In this work, lightweight composite aggregate was prepared by using discarded Al2O3-ZrO2-C refractories as the main raw material, and the performance of the prepared lightweight aggregate was improved by adjusting the calcination temperature and introducing light calcined magnesia additives. The results showed that the cold compressive strength and thermal shock resistance of the lightweight aggregates were significantly improved with increasing calcination temperature. Moreover, the introduction of light calcined magnesia can effectively improve the apparent porosity, cold compressive strength, and thermal shock resistance of the prepared lightweight aggregates at the calcination temperature of 1400 °C. Consequently, this work provides a useful reference for the resource utilization of used refractories, while the prepared lightweight aggregates are expected to be applied in the field of high-temperature insulation.

Purging plugs made of corundum–spinel castables containing Cr2O3 have been widely utilized in secondary refining process. However, their poor thermal shock resistance has greatly limited the improvement of their service life. Aiming to enhance their properties, we introduced alumina bubbles (ABs) to corundum–spinel castables, and the effects of the AB addition on the properties of the castables are studied in this manuscript. The results indicate that the apparent porosity, permanent linear change, cold strength, and hot strength all increased with an increasing AB amount. The thermal shock resistance of the samples with the AB addition was improved; the residual strength and residual strength ratio of the sample with 4 wt% ABs was the best. The effects of ABs on the tabular alumina aggregate distribution and relationship between the cold strength of the samples and the AB content was evaluated via the box dimension method. With the increments of AB content, the box dimension value of the tabular alumina within the samples significantly decreased, indicating that the tabular alumina aggregate distribution was related to the amount of ABs. In addition, the relationship between the box dimension and the strength was also established.

The ongoing development of maritime powers has driven markedly growing requirements for novel naval and civilian vessel categories in recent years. The import temperature of gas turbines is rising, and the issue of corrosion can no longer be ignored, creating an urgent need to develop coatings with high-temperature resistance, corrosion resistance, and good toughness. This study utilized plasma spraying technology to prepare composite AT13 ceramic coatings with 0 wt.%, 5 wt.%, 10 wt.%, and 15 wt.% GO/Cu (GO:Cu = 1:10) content. It systematically investigated the effects of GO/Cu doping on the porosity, Vickers hardness, fracture toughness, thermal shock resistance, and corrosion resistance of the AT13 coatings while exploring the corrosion behavior of the composite coatings. The experimental results indicate that doping with GO/Cu can effectively fill the pores of the coatings, leading to an overall improvement in coating performance. The coating with 10 wt.% doping (G2) exhibited the best comprehensive performance, with a 72% reduction in porosity compared to the original coating, a 23.2% increase in Vickers hardness, a 31.4% enhancement in fracture toughness, and an 83% decrease in corrosion rate. It also demonstrated the best thermal shock resistance, maintaining a relatively intact surface after 31 days of immersion in artificial seawater, with only a few pitting and cracking defects observed in the areas of corrosion.

Cordierite diesel particulate filters (DPFs) were prepared using pure cordierite powder with organic binders, sodium silicate aids and pore formers by extrusion technique. The orthogonal test method was adopted to investigate the optimal value of the multi-objective and multi-factor problems. Based on results from statistical analysis, sintering temperature is the most important factor. The optimal parameters for balanced overall performance were determined as a 3 h holding time, 10 wt.% pore former, 12 wt.% sintering aid, and a sintering temperature of 1150 °C, representing a compromise among the individually optimal conditions for porosity, compressive strength, and thermal shock resistance identified by range analysis. The sodium silicate liquid increased and viscosity decreased with the increasing of temperature, which led to the formation of glass phases and the improvement of density. Therefore, with increasing sintering temperature, the porosity and coefficient of thermal expansion decreased. Both the mechanical properties and chemical stability of the prepared samples are strengthened. When the sintering temperature was 1150 °C, the prepared samples with high porosity (56.04%), compressive strength (5.88 MPa), bending strength (13.10 MPa), and low thermal expansion coefficient (CTE, 1.82 × 10 /°C) showed the best comprehensive performance of thermal shock resistance and filtration efficiency. These results demonstrate great potential for DPF applications and provide a reference for the design of other honeycomb ceramics with optimum level of liquid phase.

Yttria-stabilized zirconia (YSZ) fiber composites are highly efficient thermal insulating materials; however, the poor thermal shock resistance limits their versatile applications. In the present study, YSZ fiber was mixed directly with Al2TiO5 fiber, which had an extremely low thermal expansion coefficient, to prepare YSZ−Al 2 TiO 5 (ZAT) fiber composites by compression molding and heat treatment. The minimum thermal expansion coefficient of the prepared ZAT fiber composites was measured to be 7.74×10 −6 K −1 , which was 26% lower than that of the YSZ fiber composites (10.42×10 −6 K −1 ). It was shown that the prepared ZAT fiber composites maintain the integrity after undergoing 51 thermal shock cycles between 1100 °C and room temperature. Whereas, YSZ fiber composites burst immediately after only one thermal shock cycle under the same condition. In addition, the ZAT fiber composites also exhibit considerable mechanical and thermal insulating performance.

To reveal the thermal shock resistance of double-layer thermal barrier coatings (TBCs), two types of TBCs were prepared via atmospheric plasma spraying, i.e., Gd2Zr2O7/yttria-stabilized zirconia (GZ/YSZ) TBCs and La2Zr2O7 (LZ)/YSZ TBCs, respectively. Subsequently, thermal cycling tests of the two TBCs were conducted at 1100 °C and their thermal shock resistance and failure mechanism were comparatively investigated through experiments and the finite element method. The results showed that the thermal shock failure of the two TBCs occurred inside the top ceramic coating. However, the GZ/YSZ TBCs had longer thermal cycling life. It was the mechanical properties of the top ceramic coating, and the thermal stresses arising from the thermal mismatch between the top ceramic coating and the substrate that determined the thermal cycling life of the two TBCs together. Compared with the LZ layer in the LZ/YSZ TBCs, the GZ layer in the GZ/YSZ TBCs had smaller elastic modulus, larger fracture toughness, and smaller thermal stresses, which led to the higher crack propagation resistance and less spallation tendency of the GZ/YSZ TBCs. Therefore, the GZ/YSZ TBCs exhibited superior thermal shock resistance to the LZ/YSZ TBCs.

To solve the problem of poor high-temperature service performance caused by low carbonization of MgO–C refractories, low-carbon MgO–C refractories with excellent thermal shock, oxidation and corrosion resistances were successfully designed by using SiC whiskers as reinforcing phases and introducing micro-Al 2 O 3 powders as additives. The results indicated that the addition of micro-Al 2 O 3 powders optimized the internal structure of the material, like the columnar β-Si 3 N 4 with a stepped distribution and the mosaic structure formed between granular and flaky Mg 2 SiO 4 , which synergistically strengthened and toughened the material and gave the material excellent mechanical properties and thermal shock resistance. Specifically, the cold modulus of rupture and cold crushing strength after thermal shock were increased by 4.1 and 20.3 MPa, respectively. Moreover, the addition of micro-Al 2 O 3 powders promoted the formation of fine particles of Mg 2 SiO 4 , MgAl 2 O 4 and MgO, as well as a dense protective layer of Mg 2 SiO 4 in the material under high-temperature environment. Furthermore, spinel and high-temperature solid solution were formed in the corrosion environment. The oxidation and corrosion resistances were greatly improved by 41% and 15%, respectively.

Background Ceramic matrix composites are promising materials for high temperature application in aerospace and nuclear engineering. In these applications, thermal shock is an important potential cause for failure. Objective In order to study thermal shock resistance of SiC/SiC composite braided tubes, a novel method has been developed to apply thermal shock cycles to tube sections and then measure the residual tensile strength. Methods SiC/SiC composite braided tubes have been thermally shocked by many cycles in a short time using a novel test platform based on quartz lamp irradiation heating. The circumferential tensile strength was measured using C-ring specimens after thermal shock testing of short tube sections. Numerical simulations of the stress from the thermal shock test were conducted using the finite element method. Results The circumferential tensile strength decreased with increasing number of thermal shock cycles in air. An embrittled region with limited fiber pullout due to oxidation extended from the surface. Conclusions The test platform can simulate service environments with fast temperature cycling for small test specimens in air.

MgO–C refractories with stainless steel fibers were prepared to investigate the effects of stainless steel fibers addition on the thermal shock resistance, oxidation resistance, and microstructure of MgO–C refractories, and the optimum amount of stainless steel fibers was determined. The results showed that adding stainless steel fiber in MgO–C refractories can increase flexural strength and thermal shock resistance, with an optimal addition of 2 wt.%, owing to the bridging effect and crack deflection toughening of stainless steel fibers inside the material. The formation of MgAl 1.9 Fe 0.1 O 4 composite spinel, which was responsible for higher oxidation resistance, produced volume expansion and prevented the diffusion of oxygen. The strengthening mechanism is physical embedding at room temperature, while it is reaction bonding at high temperature.