The purpose of this paper is to study the thermal shock resistance and failure mechanism of La₂Ce₂O₇/8YSZ double-ceramic-layer thermal barrier coatings (LC/8YSZ DCL TBCs) under extreme temperature gradients. At high surface temperatures, thermal shock and infrared temperature measuring modules were used to determine the thermal cycling life and insulation temperature of LC/8YSZ DCL TBCs under extreme temperature gradients by an oxygen–acetylene gas flame testing machine. A viscoelastic model was used to obtain the stress law of solid phase sintering of a coating system using the finite element method. Results and Conclusion: (1) Thermal cycling life was affected by the surface temperature of LC/8YSZ DCL TBCs and decreased sharply with the increase of surface temperature. (2) The LC ceramic surface of the failure coating was sintered, and the higher the temperature, the faster the sintering process. (3) Accelerated life test results showed that high temperature thermal cycling life is not only related to thermal fatigue of ceramic layer, but is also related to the sintering degree of the coating. (4) Although the high temperature thermal stress had great influence on the coating, great sintering stress was produced with sintering of the LC ceramic layer, which is the main cause of LC/8YSZ DCL TBC failure. The above results indicate that for new TBC ceramic materials, especially those for engines above class F, their sinterability should be fully considered. Sintering affects the thermal shock properties at high temperature. Our research results can provide reference for material selection and high temperature performance research.

Using the supersonic plasma spraying (SPS) technique, the preparation of a NiCrBSi (Ni60) coating was achieved by adding nano TiO₂ in Ni60 coating with WC ceramic particles. Ni60-TiO₂ (Ni60T) and Ni60-TiO₂/WC coating (Ni60TW) were successfully prepared. Results show that of the three, Ni60T had the best densification, the porosity of the Ni60T coating exhibited the best value of 1.3%, and also has a stronger hardness value of 890 HV. At the same time, the coating corrosion resistance, wear coefficient, and the wear morphology of Ni60T are superior to Ni60 and Ni60TW coatings. It is added TiO₂ and ceramic WC(Co) in Ni-based spraying powder. The main purpose is for the nanoparticles to achieve the effect of refining the grain, which can greatly improve the coating’s hardness and toughness.

In engineering components, crack identification plays an important role in ensuring structural safety, prolonging service life, reducing maintenance costs and improving detection efficiency. This paper proposes a crack identification approach integrating the partition of unity extended finite element method (PU-XFEM) and network-optimized fusion prediction model. Firstly, the PU-XFEM is employed to analyze the cracks of the structural component and obtain the displacement field variables of the structural surface. The sampling method of statistical analysis is used to arrange measuring points on the surface of the component. Subsequently, the displacement changes at the selected measuring points are employed as sample data and input into the constructed neural network model. To solve the limitation that the network model is prone to over-fitting and falling into local optimization, four optimization algorithms (Marine Predator Algorithm, Honey Badger Algorithm, Moth Firefly Optimization Algorithm, and Aquila Optimizer) are employed to optimize and enhance the model parameters. Then, a network-optimized fusion model of crack identification is developed by integrating the optimization algorithms with the neural network. To assess the ability of the optimization algorithms, nine test functions with diverse characteristics are selected. The efficacy of these algorithms in optimizing neural network parameters is evaluated by examining their convergence precision and rate. Ultimately, the proposed approach is validated by a series of examples. The outcomes of the network-optimized fusion model are promising, particularly in terms of data fitting and crack identification.

The preparation technology of graphene-based coatings on cobalt-based cemented carbides and the friction properties of graphene-based coatings were researched. Based on cooling rate, growth temperature, and methane flow rate, Raman spectroscopy was used to evaluate the influence of chemical vapor deposition (CVD) on graphene-based coatings. The results show that at the growth temperature of 1000 °C, the cooling rate of 15 °C/min and methane flow rate of 10 sccm are more favorable for the growth of pure graphene coating with fewer layers on a cemented carbide surface. As methane flow boosts, the number of graphene layers increases and amorphous carbon is generated. The resulting tribological properties demonstrate that the friction coefficient of graphene-based coatings decreases as the friction load increases. The above results indicate that the graphene-based coating on a cemented carbide surface can be prepared by regulating its composition and defects through technological parameters, and it is viable to use graphene-based coating as anti-wear coating for cutting tools. The results provide a reference for the preparation and properties of cemented carbide surface graphene.

The quest for superior wear-resistant coatings has led to significant advancements in laser cladding technology, yet the escalating requirements for durability under operational conditions challenge the efficacy of existing solutions. This investigation delves into the enhancement of wear resistance in coatings through the integration of particle reinforcement phases, identified as a cost-effective strategy for augmenting coating performance. Emphasis is placed on the systematic classification of particle reinforcements and the methodologies employed for their incorporation. The focus is particularly cast on the incorporation of hard and self-lubricating particles into laser-clad wear-resistant coatings, highlighting innovations in particle addition techniques. An examination of the mechanisms through which hard particles-comprising oxides, carbides, nitrides, borides, and their multifaceted compounds-reinforce coatings is presented, delineating the influence of particle content, size, and morphology on wear resistance. Additionally, the paper explores the state of research on the self-lubricating properties imparted by sulfides, fluorides, graphite, and MAX phase particles under varied thermal conditions. A critical analysis of the benefits and limitations associated with the use of hard and self-lubricating particles in the enhancement of coating durability is conducted. This comprehensive review serves not only to elucidate the current landscape of particle-reinforced, laser-clad coatings but also to inform future research directions aimed at developing coatings capable of withstanding high temperatures and exhibiting exceptional hardness. The commitment to leveraging in situ synthesis for the development of these advanced materials underscores the potential for significant breakthroughs in the field of wear-resistant coatings.

Abnormal tool wear is a significant problem encountered in machining. MoS2 has the function of friction reduction; thus, to mitigate friction, two Ni-based coatings, Ni60 and Ni60 + 15 wt.% Ni/MoS2, were obtained on tungsten steel using supersonic plasma technology. The microstructure, phase structure, microhardness, fatigue properties, and friction and wear properties of the two coatings were characterized. The results show that the two plasma-sprayed Ni-based coatings have desirable structures. The addition of Ni-coated MoS2 can effectively improve the hardness of the coatings, with values reaching as high as 735 HV. The speed of rotation of the friction ball was set as 200 r/min, and the cutting force was 201.6 N. The fatigue performance as well as the friction and wear performance of the coating are simulated using ANSYS. The fatigue performance is improved by 12.6 % after adding 15 wt.% Ni/MoS2, and the friction system of the coating becomes stable after 25 min of contact. The addition of 15 wt.% Ni/MoS2 can effectively improve the performance of the tool material.