等离子喷涂金属基热障涂层的研究

简述了金属基热障涂层的结构设计，等离子喷涂层制造工艺特点，影响因素，以及热障涂层的应用。     

应用等离子喷涂热障陶瓷工艺修复德士古烧嘴

介绍等离子喷涂热障陶瓷技术在德士古烧嘴修复中的应用，从理论和实践中对此工艺方法的可行性进行论证，并提出存在问题和今后研究方向。     

等离子喷涂陶瓷涂层综述

本文综述了利用等离子技术喷涂高性能陶瓷涂层的技术特点和应用情况以及几种热点陶瓷涂层的特性,指出了等离子技术喷涂陶瓷涂层中存在的问题,分析了可行的解决方法。     

等离子喷涂羟基磷灰石涂层

羟基磷灰石由于具有优良的生物性能，被广泛应用于生物材料领域，而等离子喷涂制备羟基磷灰石涂层是应用最为广泛的制备方法之一。在综合国内外献的基础上，本从羟基磷灰石的本征性能、喷涂工艺的影响、结合强度和梯度涂层等方面进行综述。     

等离子体喷涂厚热障涂层的研究进展

厚热障涂层(TTBCs)具有良好的隔热性能,能够有效提高航机涡轮/燃机透平前的燃气入口温度.等离子体喷涂工艺是制备TTBCs的典型方法.综述了等离子体喷涂TTBCs的国内外研究现状,指出了TTBCs所面临的挑战.着重从单片层、涂层结构及性能等方面展开探讨,同时对其发展趋势进行了展望.     

等离子喷涂羟基磷灰石涂层

羟基磷灰石由于具有优良的生物性能，被广泛应用于生物材料领域，而等离子喷涂制备羟基磷灰石涂层是应用最为广泛的制各方法之一。在综合国内外文献的基础上，本文从羟基磷灰石的本征性能、喷涂工艺的影响、结合强度和梯度涂层等方面进行综述。     

等离子喷涂陶瓷涂层的界面研究

介绍了等离子喷涂陶瓷涂层的界面特征,综述了等离子喷涂涂层的界面物理化学特性,在此基础上总结提出涂层界面设计与控制的几个先进途径,并探讨了等离子喷涂陶瓷涂层的界面研究的重点与难点问题.     

等离子喷涂陶瓷涂层的现状与应用

本文综述了陶瓷涂层的等离子喷涂制备方法、工艺特点以及陶瓷涂层在各领域中的应用,介绍了目前常用的等离子喷涂陶瓷材料,并对等离子喷涂陶瓷涂层的发展趋势进行了展望.     

Thermal Stability of Air Plasma Spray and Solution Precursor Plasma Spray Thermal Barrier Coatings

Yttria-stabilized zirconia (7YSZ) thermal barrier coatings (TBCs) were produced by conventional air plasma spray (APS) and solution precursor plasma spray (SPPS) processes. Both TBCs were isothermally heat treated from 1200° to 1500°C for 100 h. Changes in the phase content, microstructure, and hardness were investigated. The nontransformable tetragonal ( t ') phase is the predominant phase in both the as-sprayed APS and SPPS TBCs. APS and SPPS coatings exhibit similar thermal stability behavior such as densification rate, hardness increase, and grain coarsening rate. Both the as-received and heat-treated APS and SPPS TBCs show a bimodal pore size distribution with nano- and micro-size pores. After 1400°C/100 h heat treatment, equiaxed grains replace the columnar structure in APS TBCs and the splat structure disappears. Vertical cracks remain after the 1500°C/100 h exposure in SPPS TBCs. The monoclinic phase appears in APS TBCs after a 1400°C/100 h exposure and in SPPS coatings after a 1500°C/100 h exposure.     

Topographical and Microstructural Property Evolution of Air Plasma‐Sprayed Zirconia Thermal Barrier Coatings

The effects of process parameters on thermal barrier coating (TBC) formation and microstructural properties have been studied. Further understanding of the evolution of properties such as porosity and hardness is an important aspect in the design of efficient TBCs. Plasma‐sprayed yttria‐stabilized zirconia was coated onto mild steel substrates. The torch was held perpendicular to the substrate to form cone‐shaped deposits. Standoff distance (SOD) (80, 90, and 120 mm) and time (15, 30, and 60 s) were altered to investigate the microstructural property relationships of the coatings. Shape characteristics of the coatings were measured via a coordinate measuring machine, and surface roughness measurements were acquired using a 3D optical profiler. The deposition efficiency and coating roughness were affected by SOD and the evolving contour of the underlying surface. Hardness and porosity profiles were mapped to display the effect of process parameters. Dynamic parameters such as particle trajectory, evolving impact angle and dwell time affected changes in porosity, hardness, and density for each coating profile.     

陶瓷涂层热喷涂制备工艺

热喷涂陶瓷涂层将陶瓷材料耐高温、耐磨、耐腐蚀及隔热、绝缘等性能与金属材料的特点有机地结合起来。本文介绍了陶瓷涂层的热喷涂方法及工艺。     

Fatigue of Thick Thermal Barrier Coatings

Thick thermal barrier coatings (TTBCs) of plasma-sprayed 8% Y₂O₃–ZrO₂ were fatigued in compression as part of a reliability and durability study to evaluate their potential use in high-performance diesel engines. Test specimens were designed to test the bulk ceramic uniaxialiy, independent of the substrate. A test machine was designed to alleviate the mechanical gripping and alignment difficulties associated with cyclically stressing brittle ceramics in compression. Higher fatigue limits, 375 vs 200 MPa, were observed at 800°C than at room temperature. Specimens tested at room temperature after high-temperature com-pressive cycling also had higher fatigue limits, indicating that the strengthening was permanent. At temperatures of 800°C, the coatings showed evidence of low-temperature, pressure-induced sintering. The extent to which sintering occurred was determined by studying the change in the elastic modulus as a result of the application of varying temperatures and static stresses.     

热障涂层材料研究进展

热障涂层材料广泛应用于发动机热端部件的热防护,能有效提高航空发动机热端 部件的工作温度和使用寿命。目前商用的热障涂层材料为氧化钇部分稳定氧化锆,但其在服役 温度高于 1200?C 时会发生相变而失效,难以满足新一代航空发动机对热障涂层的性能要求。因 此,寻找新型热障涂层材料及其服役性能研究一直是近年来的热点。本文综述了近年来氧化钇 稳定氧化锆、钙钛矿氧化物、烧绿石氧化物以及稀土硅酸盐材料的研究进展,并展望了热障涂 层材料的未来发展趋势。     

Tribological Characterization of WC–Co Plasma Sprayed Coatings

Atmospheric plasma spraying of WC coatings is typically characterized by increased decarburization, with a consequent reduction of their wear resistance. Indeed, high temperature and oxidizing atmosphere promote the appearance of brittle crystalline and amorphous phases. However, by using a high helium flow rate in a process gas mixture, plasma spraying may easily be optimized by increasing the velocity of sprayed particles and by reducing the degree of WC dissolution. To this purpose, a comparative study was performed at different spray conditions. Both WC–Co powder and coating phases were characterized by X-ray difraction. Their microstructure was investigated by scanning electron microscopy. Mechanical, dry sliding friction, and wear tests were also performed. The wear resistance was highly related to both microstructural and mechanical properties. The experimental data confirmed that high-quality cermet coatings could be manufactured by using optimized Ar–He mixtures. Their enhanced hardness, toughness, and wear resistance resulted in coatings comparable to those sprayed by high velocity oxygen-fuel.     

Gadolinium Zirconate/YSZ Thermal Barrier Coatings: Plasma Spraying,Microstructure, and Thermal Cycling Behavior

Processing of Gd₂Zr₂O₇ by atmospheric plasma spraying (APS) is challenging due to the difference in vapor pressure between gadolinia and zirconia. Gadolinia is volatilized to a greater extent than zirconia and the coating composition unfavorably deviates from the initial stoichiometry. Aiming at stoichiometric coatings, APS experiments were performed with a TriplexPro^? plasma torch at different current levels. Particle diagnostics proved to be an effective tool for the detection of potential degrees of evaporation via particle temperature measurements at these varied current levels. Optimized spray parameters for Gd₂Zr₂O₇ in terms of porosity and stoichiometry were used to produce double‐layer TBCs with an underlying yttria‐stabilized zirconia (7YSZ) layer. For comparison, double layers were also deposited with relatively high torch currents during Gd₂Zr₂O₇ deposition, which led to a considerable amount of evaporation and relatively low porosities. These coatings were tested in thermal cycling rigs at 1400°C surface temperature. Double layers manufactured with optimized Gd₂Zr₂O₇ spray parameters revealed very good thermal cycling performance in comparison to standard 7YSZ coatings, whereas the others showed early failures. Furthermore, different failure modes were observed; coatings with long lifetime failed due to TGO growth, while the coatings displaying early failures spalled through crack propagation in the upper part of the 7YSZ layer.     

Erosion-Indicating Thermal Barrier Coatings Using Luminescent Sublayers

A successful approach to producing thermal barrier coatings (TBCs) that are self-indicating for location and depth of erosion is presented. Erosion indication is demonstrated in electron-beam physical vapor-deposited (EB-PVD) TBCs consisting of 7 wt% yttria-stabilized zirconia (7YSZ) with europium-doped and terbium-doped sublayers. Multiple-ingot deposition was utilized to deposit doped layers with sharp boundaries in dopant concentration without disrupting the columnar growth that gives EB-PVD TBCs their desirable strain tolerance. TBC-coated specimens were subjected to alumina-particle-jet erosion, and the erosion depth was indicated under ultraviolet illumination by the luminescence associated with the sublayers exposed by erosion. Sufficiently distinct luminescent sublayer boundaries were retained to maintain an effective erosion-indicating capability even after annealing free-standing TBCs at 1400°C for 100 h.     

CMAS-Resistant Thermal Barrier Coatings (TBC)

Electron beam-physical vapor-deposited thermal barrier coatings (TBC) are susceptible to damage due to environmental contaminants such as calcium–magnesium–aluminum–silicon oxide systems (CMAS). This paper discusses various approaches of modifying TBC for enhanced protection against CMAS attack. Methodologies were explored with various coating systems maintaining functionality as nonwetting, sacrificial, and impervious to CMAS attack. In the brief isothermal (1260°C/10 min) tests, a nearly crack-free and reglazed Pd coating provided substantial protection from the CMAS attack. Approaches that provided some minor improvements need further optimization to better assess their viability.