超声速等离子喷涂Ni60A涂层的滚动接触疲劳寿命*

制备高质量的超声速等离子喷涂Ni60A涂层,并研究该涂层的滚动接触疲劳性能及寿命。通过正交试验对Ni60A涂层的4个主要喷涂工艺参数(喷涂电压、喷涂电流、Ar气流量和喷涂距离)进行优化设计,通过分析孔隙率和显微硬度值的大小,综合评价喷涂层质量。利用Image J2x孔隙率计算软件计算涂层孔隙率,利用扫描电镜分析Ni60A粉末和喷涂层的微观结构,采用显微硬度计测定涂层的显微硬度,利用RM-1接触疲劳/磨损多功能试验机对涂层进行不同载荷条件下的接触疲劳试验,并建立Weibull失效概率图。结果表明,通过正交试验可以获得高质量的超声速等离子喷涂Ni60A涂层,超声速等离子喷涂Ni60A涂层的最优喷涂工艺参数为：喷涂电压170 V,喷涂电流370 A,Ar气流量110 L/min,喷涂距离110 mm,通过最优参数制备得到的Ni60A涂层的孔隙率为1.05%,显微硬度为1 086 HV_0.2;在不同接触应力水平下,Ni60A涂层的寿命服从Weibull分布,通过Weibull失效概率图可以在一定范围内预测某一工作载荷下涂层的接触疲劳寿命。     

喷涂功率对碳/碳复合材料表面羟基磷灰石涂层抗剪强度的影响

采用等离子喷涂技术在碳／碳复合材料表面制备了羟基磷灰石（HA）涂层,采用自制装置测定了不同喷涂功率下涂层与基体的抗剪强度,采用扫描电镜观察了涂层表面、横截面和剪切断裂表面的微观形貌,并分析了涂层与基体的剪切断裂失效形式。结果表明：在40kw喷涂功率下,涂层与基体的抗剪强度最高,约为10MPa,其剪切断裂失效方式主要为涂层内部失效。     

激光重熔纳米SiC复合陶瓷涂层组织和性能研究

研究了WC／Co-NiCrAl等离子复合陶瓷涂层、激光重熔等离子涂层、激光渗入纳米SiC涂层的组织结构、耐磨性能。结果证明：在所定的工艺参数下，等离子喷涂层组织呈层片状，层间为机械结合界面；经激光重熔后，激光作用区涂层组织细化，孔隙率降低，耐磨性能是原等离子涂层的1．3倍；渗入纳米SiC后，组织进一步细化，孔隙率进一步降低，SiC颗粒仍处于纳米尺度，分布在粗颗粒表面及粗颗粒之间，其耐磨性能是原等离子涂层的2．6倍。     

Investigation of deformation behavior and fracture of ceramic coatings by the acoustic emission method

The use of protective coatings on components of machines and mechanisms provides the greatest economic benefit at the lowest additional cost. Plasma spraying is one of the most productive, technologically advanced, and efficient methods of producing these coatings. The results of investigations of structures, mechanical properties, and fracture surfaces of ceramic wear resistant coatings produced by plasma spraying have been presented.     

Effects of the nozzle design on the properties of plasma jet and formation of YSZ coatings under low pressure conditions

How to control the quality of the coatings has become a major problem during the plasma spraying. Because nozzle contour has a great influence on the characteristic of the plasma jet, two kinds of plasma torches equipped with a standard cylindrical nozzle and a converging-diverging nozzle are designed for low pressure plasma spraying(LPPS) and very low pressure plasma spraying(VLPPS). Yttria stabilized zirconia(YSZ) coatings are obtained in the reducing pressure environment. The properties of the plasma jet without or with powder injection are analyzed by optical emission spectroscopy, and the electron temperature is calculated based on the ratio of the relative intensity of two ArⅠspectral lines. The results show that some of the YSZ powder can be vaporized in the low pressure enlarged plasma jet, and the long anode nozzle may improve the characteristics of the plasma jet. The coatings deposited by LPPS are mainly composed of the equiaxed grains and while the unmelted powder particles and large scalar pores appear in the coatings made by VLPPS. The long anode nozzle could improve the melting of the powders and deposition efficiency, and enhance the coatings' hardness. At the same time, the long anode nozzle could lead to a decrease in the overspray phenomenon. Through the comparison of the two different size's nozzle, the long anode is much more suitable for making the YSZ coatings.     

镍-铬系涂层对锅炉管材高温持久强度的影响

对等离子喷涂NiCr—Cr3C2／Ni45Cr涂层的过热器管材12Cr2MowVTiB(钢研102)在现场运行3万h后取样,与无涂层锅炉管材及未运行过的原始锅炉管材进行了高温持久强度对比试验。结果表明：涂层锅炉管持久强度性能明显优于无涂层保护炉管,据此进一步分析讨论了燃煤烟气的热腐蚀对钢研102管材持久强度的影响及涂层防护机制。     

High temperature friction and wear characteristics of various coating materials for steam valve spindle application

Various coatings such as chromium carbide (deposited by plasma spraying and detonation gun techniques), chromium oxide, chromium oxide+titania+silica, NiCrAlY, and Al₂O₃+NiAl, all deposited by plasma spraying; stelliting, and surface nitriding have been applied on X20CrMo V121 steel. This steel is used for high temperature applications such as steam turbine valve spindle. Friction and wear behavior of the surface coated and treated materials have been studied at an elevated temperature of 550°C while rubbing against graphite-filled stellited steel. These studies have been carried out on SRV Optimol reciprocating tribometer. Test parameters for tribological studies have been selected with a view to simulate operating conditions encountered in operation. Additionally, the structure, porosity, hardness, bond strength, and thermal cycling behaviour of these surface coated/treated materials have been characterised. Based on these laboratory investigations, chromium carbide coating deposited by plasma spraying technique has been identified as the most suitable coating for steam turbine valve spindle application. Process parameters have been established for deposition of chromium carbide coating by plasma spraying technique on actual valve spindles. The field results obtained are found to be commensurate with the laboratory findings.     

Influence of undercoating on rolling contact fatigue performance of Fe-based coating

The aim of this paper was to address the influence of undercoating on the rolling contact fatigue (RCF) performance of coatings. The Fe-based alloy and Ni/Al alloy were deposited on substrates as surface coating and undercoating by plasma spraying. The failure modes were investigated for two kinds of coatings. RCF performances were compared using Weibull distribution plot. The results showed undercoating played an important role on increasing RCF life of coating for the higher bond strength, and decreasing the scatter of RCF life data. The deposited undercoating could influence the failure mode of coating and prevent the occurrence of catastrophic delamination.     

发动机叶片自动化喷涂转台的设计

为了能够提高工作效率和喷涂质量,设计研制了发动机叶片自动化喷涂转台。该转台设备与ABB喷涂机械手组成了一套自动化发动机叶片喷涂设备。介绍了转台设备的机械结构、设计原理以及电控系统的实现方法。该转台设备在实际应用中取得了很好的效果,可以推广到其他复杂产品的自动化喷涂生产中。     

Abrasive wear behavior of sprayed hydroxyapitite coatings by gas tunnel type plasma spraying

Hydroxyapatite (HA) coatings were sprayed using gas tunnel type plasma spraying at different arc currents. Abrasive wear test was carried out for the coatings sprayed at different arc currents under unlubricated conditions in air atmosphere. The abrasive wear rate was measured at different coatings thickness to study the effect of coating thickness on the anti-abrasion resistance of HA coatings. The results showed that the abrasive wear resistance of HA coatings increases as the operating arc current of the plasma torch increases. On the other hand, the abrasive wear rate reaches a minimum value near the substrate with coating thickness less than 50 μm. The results showed that the coating hardness increases in the region near the substrate and increases as the arc current increases. The experimental results indicated that there is a relation between the abrasion resistance and hardness properties of HA coatings.     

ZrO2热障涂层耐高温冲刷性能研究

采用等离子喷涂工艺制备了NiCoCrAlY／ZrO2热障涂层，利用超音速火焰喷涂（HVOF）ZrO2粒子高速冲刷涂层表面，考察ZrO2热障涂层的耐高温冲刷性能。结果表明，等离子喷涂NiCoCrAlY／ZrO2热障涂层具有较好的耐高温冲刷性能，经高温高速粒子冲刷20s后，涂层与基体结合良好，涂层完整，未出现大面积的剥落。等离子喷涂ZrO2热障涂层高温冲刷的主要磨损机理为脉动冲击作用造成的裂纹扩展、涂层颗粒变形磨损和微切削。涂层的耐高温冲刷性能主要取决于涂层的硬度。     

不同喷涂工艺制备的Al_2O_3-13%TiO_2涂层表面自由能与冲蚀磨损性能研究

采用接触角测量仪和冲蚀磨损试验机等设备,研究超声速等离子喷涂与普通大气等离子喷涂两种技术制备的Al_2O_3-13%TiO_2涂层的表面自由能和冲蚀磨损性能,并对涂层的显微硬度、孔隙率及成分进行检测分析。研究结果表明,普通大气等离子喷涂技术制备的涂层,其表面和内部结构疏松,孔隙率及显微硬度分别为6.653%和836.93 HV0.1。而超声速等离子喷涂技术制备的涂层,孔隙率及显微硬度分别为3.467%和1 078.68 HV0.1,相比普通大气等离子喷涂而言,超声速等离子喷涂制备的涂层整体性能较为优异。通过对两种涂层的结构和表面自由能分析发现,超声速等离子喷涂Al_2O_3-13%TiO_2涂层由于结构致密、表面自由能较低而具有较为出色的冲蚀磨损性能。     

激光处理对Ni-P-SiC复合镀层组织与性能的影响

以不同的激光输出功率对Ni-P-SiC复合镀层进行扫描处理,借助扫描电镜、X射线衍射仪、硬度仪等对激光处理后复合镀层的表面组织及性能作了分析,并与炉中处理的镀层进行了对比。结果表明：激光处理后由于镀层中能析出较炉内处理更多的Ni3P及Ni2Si、Ni3Si等化合物,其镀层硬度明显高于炉内处理的硬度,且耐磨性也有一定的提高。     

Abrasion and corrosion resistant cobalt base alloys for hardfacing

Previous investigations carried out at CRM have shown that adding Mo, singly or in combination with Ni and/or Cu, enhances greatly the corrosion and abrasion resistance of high-carbon Co-Cr-W-C cast alloys.On account of these improvements, coatings of several Mo-, Ni- and/or Cu-modified grades of a Co-2.2% C-13% W-32% Cr alloy were prepared either by oxyacetylene welding with cast electrodes or by plasma spraying with prealloyed powders. The abrasion/corrosion behavior of the experimental deposits was compared with that of commercial alloys. The test data reported in this paper reveal the particularly good behaviour of the 18.2% Ni-4% Cu-8.7% Mo modified grade.     

Characterization and solid particle erosion behavior of plasma sprayed alumina and calcia-stabilized zirconia coatings on Al-6061 substrate

Repeated impact by solid particles causes erosion and degradation of engineering components. In internal combustion engines, during combustion, hot gases are generated in large quantity which causes erosion of cylinder, combustion chamber, exhaust system, etc. In this work, two types of plasma sprayed coating systems were developed on Al-6061 substrate. For each system, a systematic microstructural study was carried out to understand changes occurred after spraying. Mechanical properties like density, adhesion strength and hardness of coatings were determined. A solid particle erosion test was conducted on coating systems according to ASTM G-76-02 and results were correlated with the microstructural and subsequent mechanical property change. It was observed that volume erosion is more at 45° angle of impact and shows that behavior is in between ductile and brittle. This work also discusses the mechanism involved in erosion wear of plasma sprayed coating systems.     

喷涂功率对NiCr-Cr3C2涂层表面自由能及其摩擦性能的影响

利用超音速等离子喷涂技术制备了不同喷涂功率条件下的NiCr-Cr3C2涂层,结合表面自由能理论研究了其表面摩擦学性能。利用Owens-Wendt几何平均法计算了涂层的表面自由能及其分量。对比发现,涂层孔隙率、显微硬度和摩擦因数均随着喷涂功率的变化而变化,且其变化趋势与极性分量均表现出一定的相似性。分析表明,受喷涂功率的影响,喷涂粒子的温度和速度对涂层表面分子间作用力产生影响,从而间接改变了涂层表面的自由能,并且自由能及其分量的改变,会直接影响NiCr-Cr3C2涂层表面的摩擦学特性。     

The erosion and abrasion characteristics of alumina coatings plasma sprayed under different spraying conditions

A series of plasma sprayed alumina coatings was evaluated regarding their erosion and abrasion characteristics. The coatings were deposited under different spraying conditions, using a commercial axial injection plasma spray system, and with powders of different grit sizes and crystallinity. A sintered bulk alumina and a conventionally sprayed coating, produced by a radial injection air plasma spray technique, were tested as reference materials. To evaluate the importance of energy input the coatings were produced using two different torch nozzle sizes and gas mixtures with a varied amount of hydrogen. The erosion and abrasion results indicate that hydrogen concentration, nozzle size and precursor powder type and size influence the tribological characteristics of the coatings. The wear resistance of the coatings seems to benefit from an increase in hydrogen concentration or torch nozzle size. The effect of precursor powder size on the wear resistance was more complex but indicates that sapphire powders of medium precursor sizes are advantageous to ordinary plasma spraying powders of alumina.     

等离子喷涂技术研究与发展现状

本文从等离子喷涂设备、新型功能涂层、与等离子喷涂相关的测量技术等几个方面,综述了等离子喷涂技术的研究与发展现状。     

等离子喷涂PZT涂层压电性能的实验研究

对用等离子喷涂制备的锆钛酸铅 ( PZT)压电陶瓷涂层的压电性能进行了实验研究 ,分析了涂层热处理及热处理温度、喷涂工艺参数以及粉末铅含量对压电应变常数 d33的影响 ,揭示了各种工艺条件和工艺参数下 d33的变化趋势。     

等离子喷涂用纳米结构喂料的制备研究

探索了等离子喷涂用纳米结构喂料的制备工艺，并采用此方法制备了纳米结构的Al2O3-13％TiO2喂料。采用等离子喷涂工艺进行了喷涂试验。试验结果表明，该喂料可用于等离子喷涂，涂层良好。