C2H2/N2流量对反应等离子喷涂TiCN涂层影响的研究

以不同流量的C2H2与N2作为反应气体，通过反应等离子喷涂的方法制备TiCN涂层。并对涂层中物相、组织形貌和显微硬度进行比较与分析。实验结果表明，以C2H2气体流量为0．25m3／h喷涂时。所得涂层的组织致密，硬度较高；以C2H2N2流量比为1：1进行喷涂时，涂层中的氧化物含量较少，但组织致密性较差，硬度降低。     

硅灰石涂层开裂的原位观察及粉末粒度对其断裂的影响

涂层断裂分析对研究涂层的失效机制、优化制备工艺、指导涂层设计具有重要作用.通过对等离子喷涂硅灰石涂层在电镜下进行加载,原位观察其裂纹扩展路径.并通过对涂层断裂韧性及表面和断面形貌的分析,探讨涂层粒度对涂层裂纹扩展的影响.结果表明,裂纹的扩展方向主要受外加应力方向的影响,涂层中原有孔隙,包括大气孔、层内裂纹和层间未结合对开裂过程具有一定的引导作用.随粉末粒度降低,涂层的断裂路径更加曲折,断裂韧度增加.     

喷涂距离对热障涂层拉伸强度的影响

用等离子喷涂方法，在不同的喷涂距离（d）下制备出ZrO2陶瓷涂层，通过涂层的拉伸实验、X射线衍射和扫描电镜分析，研究了喷涂距离对涂层拉伸强度（σ）的影响规律。结果表明：d=70、80mm时，σ较高，最高可达9．14MPa；d〈70mm时，粘接层的氧化明显加剧，热生长氧化物的量明显增加，降低了ZrO2涂层与粘接层之间的结合强度，导致σ下降；d〉80mm时，随着喷涂粒子的速度降低，撞击到喷涂表面后不能完全铺展，导致σ下降。     

C_2H_2/N_2流量对反应等离子喷涂TiCN涂层影响的研究

以不同流量的C2H2与N2作为反应气体,通过反应等离子喷涂的方法制备TiCN涂层。并对涂层中物相、组织形貌和显微硬度进行比较与分析。实验结果表明,以C2H2气体流量为0.25m3/h喷涂时,所得涂层的组织致密,硬度较高;以C_2H_2:N_2流量比为1:1进行喷涂时,涂层中的氧化物含量较少,但组织致密性较差,硬度降低。     

梯度涂层的等离子喷涂工艺参数及其关键保证措施

梯度涂层是在涂层厚度坐标上成分比例连续（或离散）变化的一种新型涂层,等离子喷涂作为制备梯度涂层的一种方法,其工艺参数控制的有效与可靠程度直接关系到最终涂层的质量。本文从工艺系统的角度出发,探讨了梯度涂层等离子喷涂的各种工艺参数,研究了一种可行的简化方案,并提出了一些关键保证措施,为进一步的研究和实践工作提供一一些依据。     

等离子喷涂涂层锻造工艺参数优化研究

为了提高热喷涂涂层的致密度,降低涂层残余应力,提出了涂层喷涂锻造工艺.以涂层结合强度和孔隙率为目标函数,以锻造温度、锻造次数和打击能量为变量,采用正交设计法进行了涂层锻造工艺参数优化设计,确定了因素的主次关系,得到了最佳锻造工艺参数,并进行了锻造工艺试验验证.分别在30°和90°冲蚀角情况下,对未锻造试件和锻造试件进行冲蚀对比试验研究.结果表明,经喷涂锻造工艺制备的涂层耐冲蚀性能明显优于未锻造试件.     

喷涂距离对冷喷涂Al涂层性能的影响

采用冷喷涂法制备Al涂层,测定所获涂层的沉积率、显微硬度,并分析涂层与基体的结合情况,研究了喷涂距离对Al涂层的影响。结果表明,喷涂距离为30 mm时涂层的沉积率及显微硬度较高,与基体结合效果较好,而其他距离下涂层性能劣化的原因为颗粒下降速度不稳或发生粒子散射。     

Cr_3C_2-NiCr涂层等离子喷涂工艺参数的优化

采用正交试验方法研究了等离子喷涂工艺参数对Cr_3C_2-NiCr涂层显微硬度的影响,并应用极差分析方法对试验结果进行了分析.结果表明,影响涂层性能的因素从主到次依次为喷涂距离、电流、送粉气流量和电压.Cr_3C_2-NiCr涂层最佳的等离子喷涂工艺参数是电流500 A,电压65 V,喷涂距离100 mm,送粉气流量7 L/min.采用优化后的等离子喷涂工艺制备的涂层,粒子熔化充分,涂层均匀致密,孔隙率低,界面结合良好,是高质量的热喷涂涂层.     

干冰微粒喷射工艺对等离子喷涂金属涂层结构和性能的影响

干冰微粒喷射法被应用到大气等离子喷涂中以改善涂层的性能。文中采用等离子喷涂和干冰微粒喷射工艺在不锈钢基体表面制备了钢涂层,并研究了涂层的微观结构、孔隙率、温度、氧化、表面粗糙度和结合强度等性能。结果表明,由于干冰微粒喷射具有较高的冷却效率,加之干冰微粒撞击所产生的机械作用,等离子喷涂制备的钢涂层呈现出更致密的结构特征。相比于空气冷却制备的涂层,干冰微粒冷却制备的涂层含有更少的氧化物。另外,干冰微粒喷射工艺对基体的预处理使得涂层的结合强度提高了将近14%,这是由于干冰微粒喷射工艺对基体上吸附的有机物质具有清洁作用,主要基于干冰颗粒的热、机械和膨胀的综合效应。     

等离子喷涂热障涂层相结构的研究

研究了等离子喷涂两层热障涂层在大气和真空环境下，经1100℃不同时间扩散处理后相结构的变化。结果表明，喷涂过程中，ZrO2发生M相→T相转变；经大气环境扩散处理后，ZrO2发生T相→M相转变，NiCrAlY相被氧化形成Al2O2和NiAl2O4相，同时r'-Ni3Al相有强烈的择优取向。     

On-line temperature monitoring and process diagnosis of plasma sprayed coatings

On-line temperature monitoring of plasma sprayed coating is presented, which is based on IR pyrometery combined to robot trajectories. Temperature fields of the substrate before spraying and the deposited coating when the damage happens are taken to investigate the temperature fluctuation information. Experimental results demonstrate that coating damage always occurs in the temperature transition area of the substrate from the higher to the lower, as well as the higher temperature area. The temperature difference between the peak and the mean of the relevant regions is beyond 30-50 ℃ or even higher. This case provides the omen of coating damage and the focusing scopes for the process control of coating temperature in plasma spraying.     

等离子喷涂与脉冲等离子爆炸复合涂层的氧化组织分析

采用等离子喷涂在镍基高温合金GH4049表面制备了CoNiCrAlY涂层,随后对涂层进行了脉冲等离子爆炸和真空预氧化处理,并对涂层进行了1050℃保温10 h和50 h的恒温静态氧化实验。结果表明:经过脉冲等离子爆炸处理后的涂层表面形貌更加平坦,脉冲等离子爆炸处理使得涂层表面的片层结构转变为致密结构,减少了氧气渗入涂层的通道,有效延缓了涂层的氧化过程,且没有改变涂层的化学成分;在1050℃空气中氧化50 h后,涂层的物相组成与未氧化处理的基本一致。     

Effect of spray parameters on residual stress build-up of HVOF sprayed aluminium/tool-steel functionally graded coatings

The High Velocity Oxy–Fuel (HVOF) process is one of the most versatile thermal spray technologies and has found use in many industries due to its flexibility and cost effectiveness. It is normally used to protect components against wear, heat and/or corrosion and has the potential to produce functionally graded coatings. Gradual changes of microstructure in functionally graded coatings reduce possible residual stress build-up by gradually attaining property changes between the substrate and the coating. Effectively this is done by depositing layers of coatings of varying composition. The present study investigates the effect of spray parameters on residual stress build-up in aluminium/tool-steel functionally graded coatings (FGC). A simple 3³ factorial design of experiments was employed to establish the effects of spray parameters on residual stress. Residual stress was measured using Clyne's analytical method. Parameters such as flow rate ratio of the oxygen to propylene, flow rate of the compressed air and spray distance were varied during coating deposition. Apart from the thickness of the coated sample, the spray distance showed greater effect on residual stress build-up in the graded coatings compared to flow rate ratio of the oxygen to propylene, and flow rate of the compressed air. Finally a set of values of spray parameters giving the best compromise between low residual stress and high deposited coating thickness were identified. This paper concluded that the optimised set of parameters for FGC resembles the parameters recommended for the deposition of the powder with the lowest melting and boiling point; in this case aluminium.     

Erosion-resistance of plasma sprayed coatings

Cr₃C₂/NiCr, ZrO₂/NiCr, WTiC₂/NiCr, and X40 were plasma sprayed on the substrate 1Cr18Ni9Ti in order to solve the erosion wear at high temperature encountered in the oil-refining industry. A series of properties of the coatings, including their microstructure, hardness, and erosion-behavior, have been tested. The test results show that the properties of the coatings have a significant effect on their erosionresistant performance. Good erosion-resistant materials need to be hard and tough. Both Cr₃C₂/NiCr and X40 have good erosion resistance at elevated temperature.     

Antibacterial properties of vacuum plasma sprayed titanium coatings after chemical treatment

Implant-related infection is one of the common clinical complications that cause high rates of mortality and morbidity in orthopedic surgery. Endowing implant antibacterial properties is a useful method to reduce such infection. In this paper, vacuum plasma sprayed titanium coatings were treated by NaOH solution firstly, and then antimicrobial silver was introduced into the coatings by immersing in 0.02 mM (denoted as CA1), 0.06 mM (denoted as CA2) and 0.1 mM (denoted as CA3) Ag⁺ containing calcification solution. Antibacterial property of the treated titanium coatings was examined by employing three types of bacteria stains, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. X-Ray diffraction and scanning electron microscopy were used to observe the phase composition and surface morphology of the modified titanium coatings. Results showed that all of the three kinds of coatings exhibited more than 90.00% antibacterial ratio except CA1 to Staphylococcus aureus which is 63.30%. The release of silver in physiological environment was monitored and it was found that the excellent antibacterial property of the treated coatings was attributed to the release of silver.     

超音速等离子喷涂FeCrBSi涂层组织和残余应力分析

采用超音速等离子喷涂技术制备了FeCrBSi涂层,利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)和纳米压痕仪等研究了涂层的微观组织和力学性能。采用X射线应力仪对不同厚度及不同温度退火后涂层的表面残余应力进行测试。结果表明涂层表面的残余应力为拉应力,且随着涂层厚度的增加而增加;对试样进行退火处理可以有效地缓和涂层表面的残余应力,随着温度的升高涂层表面的残余应力不断降低,到260℃左右变为压应力;压应力值随着退火温度的升高而变大,但当温度升高到大约400℃以上时,保持在80 MPa左右。     

Thermal properties and microstructure of a plasma sprayed wollastonite coating

Wollastonite coatings were deposited using an atmospheric plasma spraying technique. The microstructure and phase compositions of the coating before and after heat treatment were investigated using scanning electron microscopy (SEM), x-ray diffraction (XRD), and differential thermal analysis (DTA) technologies, respectively. In addition, the coefficient of thermal expansion and thermal diffusivity of the coating were also investigated. Crystalline wollastonite, glassy phase, and tridymite (SiO₂) were observed in the coating. Tridymite (SiO₂) likely reacted with other composites such as CaO and glassy phase to form crystalline wollastonite when the coating was heated at about 882 °C. During the first thermal cycle, the coefficient of thermal expansion of the coating decreased dramatically between 700 and 850 °C and the thermal diffusivity of the coating was 2.7–3.1 × 10⁻³cm²/s between 20 and 1000 °C. During the second thermal cycle, the coefficient of thermal expansion of the coating increased slightly between room temperature and 1000 °C and the thermal diffusivity of the coating increased by about 20% compared with that of the first thermal cycle. The atmospheric plasma sprayed Wollastonite coating may be used as thermal barrier coating.     

等离子喷涂人工骨涂层材料

等离子喷涂是一种常用的生物医用材料表面改性技术,被广泛应用于钛等金属人工骨的表面改性.为了满足人工骨涂层的临床应用需要,近年来发展了一些新的涂层材料和后处理工艺技术.利用火焰蒸汽处理技术对等离子喷涂羟基磷灰石涂层进行后处理,提高了涂层的结晶度,降低其在体液中的降解.经碱处理的等离子喷涂钛涂层,生物活性有了明显的改善.等离子喷涂硅灰石和硅酸二钙陶瓷是一类不同于传统磷酸钙系的新型生物活性材料,其性能和结构已被初步研究.同时介绍了等离子喷涂人工骨涂层材料在这几个方面的近期研究进展.