热喷涂技术的发展和应用

介绍了热喷涂技术的工艺特点.对超音速火焰喷涂、超音速等离子喷涂、激光喷涂、反应热喷涂和冷喷涂等5种不同的热喷涂工艺的优缺点进行了分析.总结了热喷涂技术的应用状况.探讨了新工艺、新材料在热喷涂技术中的应用前景.     

超音速等离子喷涂制备陶瓷涂层的研究进展

超音速等离子喷涂技术由于具有高温、高速的独特优点,且制备的陶瓷涂层结合强度和致密度高,孔隙率低,具有优良的耐磨损、耐腐蚀、抗氧化和热冲击性能,已成为一些发达国家竞相研究的热点.本文介绍了常用的陶瓷涂层材料,综述了超音速等离子喷涂技术及其制备陶瓷涂层的工艺特点,并对超音速等离子喷涂制备高性能陶瓷涂层的发展趋势进行了展望.     

热喷涂技术在光催化TiO2涂层领域的研究与进展

通过对等离子喷涂、超音速火焰喷涂和液料热喷涂等热喷涂工艺在光催化TiO2涂层领域的应用分析,阐明了不同热喷涂方式对涂层性能有不同的影响,指出液料热喷涂可以较好地减少锐钛矿向金红石的转变,并能进一步细化晶粒,可以制备具有较好光催化性能的重要环保材料。而在涂层粉末中掺杂其他元素可以改善涂层的光催化性能,但如何选择合适的掺杂元素需要进行进一步的研究。     

热喷涂技术制备陶瓷涂层的研究进展

介绍了常用的热喷涂材料,综述了电弧喷涂、火焰喷涂和等离子喷涂3种制备陶瓷涂层的热喷涂技术的基本原理,展望了热喷涂技术制备陶瓷涂层的发展趋势和应用前景。     

等离子喷涂技术研究现状

概述了等离子喷涂的基本原理,并介绍了大气等离子喷涂、超音速等离子喷涂和低压等离子喷涂3种常用的等离子喷涂技术。综述了该技术在制备保护性涂层、功能性涂层以及零件修复强化方面的应用,展望了等离子喷涂技术未来的发展趋势。     

Al2O3拉晶杆的研制

该新型材料用于延长机械零件的服役期限,提高服役可靠性。研究中采用等离子喷涂技术,制备了具有耐磨、耐蚀和耐热等多功能的陶瓷梯度涂层,针对热喷涂陶瓷涂层中残余应力、微孔洞和层间界面的弱结合三大问题,研究过程中系统地研究了喷涂工艺参数、涂层结构和陶瓷材料成分对涂层组织和性能的影响。本研究将功能梯度材料设计思想运用到多功能涂层设计中,给出了适合工业应用的梯度复合结构涂层模型;在Cr2O3陶瓷材料中采用CeO2、SiO2添加剂可改善涂层的组织和性能;同时建立了涂层热震寿命预测数学模型,为涂层安全可靠工作提供了理论依据。耐磨…     

抗冲蚀性热喷涂金属陶瓷涂层研究进展

热喷涂技术是利用热源加热喷涂材料在基体表面制备涂层的方法。火焰喷涂、等离子喷涂和电弧喷涂是常用的热喷涂技术。金属陶瓷兼有陶瓷材料的高硬度、高熔点及金属的韧性等优点,常用于制备材料表面抗冲蚀涂层,其中WC系和Cr_3C_2系金属陶瓷较为常用。冲蚀工艺参数、喷涂工艺参数、喷涂材料性能对金属陶瓷涂层的抗冲蚀性能均有影响。如何通过调控材料结构和喷涂工艺参数是提高金属陶瓷涂层抗冲蚀性的关键。     

热喷涂系列综述之一:等离子喷涂

热喷涂技术是随着现代航空、航天技术的发展而发展起来的。由于涂层特别是陶瓷涂层具有耐磨、抗蚀、抗热冲击等优异性能,已广泛应用于航空、航天、军事、纺织、机械、电力、化工、生物工程等各个领域,是一项具有广阔应用前景的技术。本文简要概述了热喷涂技术,重点介绍等离子喷涂技术以及现状。     

高耐蚀耐磨非晶纳米晶复合涂层材料及制备技术

“高耐蚀耐磨非晶纳米晶复合涂层材料及制备技术”课题开发了高耐蚀耐磨非晶纳米晶复合涂层的制备技术，具有两个重要特点：一是可直接获得非晶纳米晶粉体材料，并在喷涂过程中保证粉体材料结构不发生改变，获取非晶纳米晶复合涂层；二是对非晶粉体材料，通过控制喷涂技术参数，在喷涂过程中改变、调节粉体组织结构，使得形成的喷涂涂层具有非晶纳米晶复合结构。开发了新型熔一喷硬质合金涂层的制备技术与装备，具有涂层结合强度高、组织结构致密均匀、耐腐蚀、耐磨损、耐高温、抗冲击、抗疲劳性好等特点，并可实现功能不同的梯度涂层。在北京顺义建立了热喷涂示范生产线；在哈尔滨电机厂开展了涂层性能的台架试验，对高耐蚀耐磨非晶纳米晶复合涂层在水轮机叶片上的应用开展研究，取得良好效果；在河北省梯级水电站对拟报废旧转轮进行修复，经一个汛期（三个月）的实地使用考察，涂层表现优良，获得电站专家的高度评价。申请发明专利9项。     

不同电流下超音速等离子喷涂钼-钨复合涂层的性能

将Mo粉和W粉按质量比4:1混合后用超音速等离子喷涂系统在45CrNiMoVA钢表面制备了Mo-W复合涂层。通过扫描电镜、能谱仪、X射线衍射仪、显微硬度计和摩擦磨损试验机考察了不同喷涂电流下所制涂层的微观形貌、成分、物相、显微硬度及耐磨性。结果表明,喷涂电流对Mo-W复合涂层影响显著,喷涂电流为350 A时所制涂层的各项性能最好。电流过大或过小均会导致涂层疏松,孔隙增大。Mo-W复合涂层显著提高了基体的显微硬度及耐磨性。在摩擦磨损过程中涂层和基体表面均生成了一层薄薄的耐磨氧化膜。     

热喷涂设备的发展

热喷涂技术作为一种重要的表面处理技术,近年来发展很快.本文综述了热喷涂设备(包括等离子喷涂、高速火焰喷涂、爆炸喷涂等)近年来的发展情况.     

Microstructural,mechanical and tribological properties of nanostructured YSZ coatings produced with different APS process parameters

Plasma sprayed ceramic coatings can be used in turbine engines as thermal barrier or abradable coatings, in order to improve the durability of the components as well as the efficiency. The presence of nanostructures, deriving from partial melting of agglomerated nanostructured particles, represents an interesting technological solution in order to improve their functional characteristics. In this work nanostructured yttria stabilized zirconia (YSZ) coatings were deposited by air plasma spraying (APS). The influence of the main process parameters on their microstructural, mechanical and tribological properties was investigated by scanning electron microscopy (SEM), indentation techniques at micro- and nano-scale and wear tests, respectively. Their porous microstructure was composed of well melted overlapped splats and partially melted nanostructured areas. This bimodal microstructure led to a bimodal distribution of the mechanical properties. An increase of plasma power and spraying distance was able to produce denser coatings, with lower content of embedded nanostructures, which exhibited higher elastic modulus and hardness as well as lower wear rate.     

Challenging zircon coatings by suspension plasma spraying

Zircon is a ceramic material that decomposes at high temperature, limiting its use by conventional thermal spraying. In this work, it is intended to use thermal spraying from concentrated aqueous suspensions to evaluate the possibility of obtaining coatings in which a significant proportion of zircon could be preserved. For this purpose, stable concentrated suspensions of zircon have been prepared, which have been subsequently sprayed at two different spraying distances. The coatings were characterised in terms of microstructural features and the amount of zircon present in the coatings was quantified. All the coatings obtained display the typical microstructure derived from the deposition of liquid feedstocks by plasma spraying. In all cases, the XRD analysis demonstrates the partial decomposition of zircon into zirconia and residual silica, but also that a significant percentage (about 20%) is preserved without decomposing, which marks a strong difference with respect to reported data for atmospheric plasma spraying.     

Effect of environmental pressure on the microstructure of YSZ thermal barrier coating via suspension plasma spraying

Suspension plasma spraying (SPS) as a potential technique to prepare thermal barrier coatings (TBCs) has been attracting more and more attention. However, most reports on SPS were carried out in the atmosphere. Given the unique features of in-flight particles and plasma jets under low pressure, the resulting coatings are expected to be different from those under atmospheric pressure. In this article, yttria-stabilized zirconia (YSZ) thermal barrier coatings were prepared using suspension plasma spraying under different environmental pressures. The results show that as the environmental pressure decreased, the column-like structural coating turned into a vertical crack segmented structure, as well as a dramatic decrease in surface roughness. More nanoparticle agglomerates were formed in the coating under lower environmental pressures. The real porosity of the coating increased with a decrease in environmental pressure.     

Effect of material properties on residual stress distribution in thermal barrier coatings

Residual stress has a significant influence on the crack nucleation and propagation in thermal barrier coatings (TBC) system. In this work, the residual stress in the air plasma spraying (APS) TBC system during cooling process was numerically studied, and the influence of the material properties of each layer on the residual stress was investigated. The morphologies of the interface were described by a piecewise cosine function, and the amplitude for each segment gradually increases. The elasticity, plasticity and creep of top coat (TC), thermally grown oxide (TGO) layer and bond coat (BC) were considered and the elasticity and creep of the substrate layer were taken into account. The material properties of all layers vary with temperature. The results show that the material properties have complex influence on the residual stress during cooling. The effect of the material properties of TC and BC on the residual stress at the interface is relatively large, and that of TGO and substrate is relatively small. These results provide important insight into the failure mechanism of air plasma spraying thermal barrier coatings, and important guidance for the optimization of thermal barrier coating interfaces.     

Structure and properties of plasma sprayed BaTiO3 coatings after thermal posttreatment

Previously published results on electrical and mechanical properties of BaTiO₃ coatings prepared by atmospheric plasma spraying showed anomalies in their dielectric response. This paper provides a study of electrical and mechanical properties of BaTiO₃ coatings after thermal posttreatment. The spraying was carried out by a direct current gas-stabilized plasma gun. BaTiO₃ was fed into the plasma jet as a feedstock powder prepared by reactive sintering of micrometer-sized powders of BaCO₃ and TiO₂. In the next step the coatings were annealed in air. Microstructure and phase composition are reported and discussed in relation to electric and mechanical properties. Dielectric properties are reported for the radio frequency (RF) range.     

热喷涂陶瓷涂层的耐磨应用及涂层结构调控方法

因涂层材料适用范围广、基材适应性强、工艺灵活等特点,热喷涂陶瓷涂层作为一类新型耐磨涂层已经在很多领域获得成功应用。然而,现代工业发展对耐苛刻条件下严酷磨损的高性能耐磨涂层提出了越来越高的需求,如何通过材料?工艺的整体技术体系进行涂层结构的有效调控,成为涂层技术领域的重要研究课题之一。本文在简要介绍热喷涂陶瓷涂层作为耐磨涂层应用现状的基础上,提取出对涂层耐磨性具有普遍意义的层内扁平粒子间界面结合这一重要的涂层结构本质特征,明确了涂层内扁平粒子间界面强化的基本思路,阐述了基于界面同质强化和界面异质强化的两条思路进行层间结合界面强化的研究进展,以期为面向更高耐磨性能的热喷涂陶瓷涂层的材料选择、结构设计以及工艺优化提供有益参考。     

Characterization of Thermal Barrier Coatings Produced by Various Thermal Spray Techniques Using Solid Powder,Suspension, and Solution Precursor Feedstock Material

Use of a liquid feedstock in thermal spraying (an alternative to the conventional solid powder feedstock) is receiving an increasing level of interest due to its capability to produce the advanced submicrometer/nanostructured coatings. Suspension plasma spraying (SPS) and solution precursor plasma spraying (SPPS) are those advanced thermal spraying techniques which help to feed this liquid feedstock. These techniques have shown to produce better performance thermal barrier coatings (TBCs) than conventional thermal spraying. In this work, a comparative study was performed between SPS‐ and SPPS‐sprayed TBCs which then were also compared with the conventional atmospheric plasma‐sprayed (APS) TBCs. Experimental characterization included SEM, porosity analysis using weight difference by water infiltration, thermal conductivity measurements using laser flash analysis, and lifetime assessment using thermo‐cyclic fatigue test. It was concluded that SPS coatings can produce a microstructure with columnar type features (intermediary between the columnar and vertically cracked microstructure), whereas SPPS can produce vertically cracked microstructure. It was also shown that SPS coatings with particle size in suspension (D₅₀) <3 μm were highly porous with lower thermal conductivity than SPPS and APS coatings. Furthermore, SPS coatings have also shown a relatively better thermal cyclic fatigue lifetime than SPPS.     

镁合金陶瓷涂层研究现状

叙述了镁合金的优缺点以及金属基陶瓷涂层的特征。介绍了3种镁合金表面陶瓷涂层的制备方法(包括热喷涂法、微弧氧化法和热化学反应法)的特点及研究现状。指出了今后镁合金陶瓷涂层的发展趋势。