电磁加速等离子喷涂法制备碳化硼涂层初步分析

利用自制的电磁加速等离子喷涂装置在45钢基体上制备了碳化硼涂层，运用扫描电镜、能谱分析及X射线衍射分析对碳化硼涂层的形貌和相组成进行了定性的分析。实验结果表明：利用自制的电磁加速等离子喷涂装置成功地制备了碳化硼涂层，单次喷涂厚度在11～12μm。所制备的碳化硼涂层中除了含有碳化硼外，还含有B和C的一些其他相。     

等离子喷涂对涂层非晶含量的影响

选用一种Fe基非晶粉末,利用等离子喷涂技术在不同喷涂电流和气体流量参数下制备涂层.用X射线衍射仪分析涂层非晶相对含量,对纯非晶涂层和含有纳米晶粒非晶复合涂层分别进行透射电镜观察.通过调整等离子喷涂电流和气体流量获得不同非晶含量非晶涂层,并分析其形成原因.     

Development of Expert Controller for Plasma Spraying Process

SOME PLASMA SPRAYING EQUIPMENTS ofnewly-developed have been added system monitorfunction and system self-diagnosis,alarming andamendment are realized,and the coating qualitycontrol can be achieved by setting up information baseof control parameters.But investigation of plasmaspraying technology is mainly concentrated onspraying process and coating properties in our country['2].In this paper,plasma spraying parameters andcoating properties and relationship between them areanalyzed by …     

Suspension Plasma Spraying: Process Characteristics and Applications

Suspension plasma spraying (SPS) offers the manufacture of unique microstructures which are not possible with conventional powdery feedstock. Due to the considerably smaller size of the droplets and also the further fragmentation of these in the plasma jet, the attainable microstructural features like splat and pore sizes can be downsized to the nanometer range. Our present understanding of the deposition process including injection, suspension plasma plume interaction, and deposition will be outlined. The drawn conclusions are based on analysis of the coating microstructures in combination with particle temperature and velocity measurements as well as enthalpy probe investigations. The last measurements with the water cooled stagnation probe gives valuable information on the interaction of the carrier fluid with the plasma plume. Meanwhile, different areas of application of SPS coatings are known. In this paper, the focus will be on coatings for energy systems. Thermal barrier coatings (TBCs) for modern gas turbines are one important application field. SPS coatings offer the manufacture of strain-tolerant, segmented TBCs with low thermal conductivity. In addition, highly reflective coatings, which reduce the thermal load of the parts from radiation, can be produced. Further applications of SPS coatings as cathode layers in solid oxide fuel cells (SOFC) and for photovoltaic (PV) applications will be presented.     

氧—乙炔火焰熔凝Ni-Cr-B-Si合金粉末等离子喷涂层

用氧—乙炔火焰对Ni-Cr-B-Si合金粉末等离子喷涂层进行了快速熔敷处理,结果表明,熔敷处理后的喷涂层的耐磨性和抗蚀性都有明显提高。     

ZrO2纳米粉等离子喷涂工艺及磨损性能研究

应用spraywatch热喷涂在线监测系统测定了ZrO2纳米粉等离子喷涂工艺参数与喷涂粒子温度和速度的关系；测定了涂层耐磨性，分析了涂层表面形貌、界面结合状况和物相组成；获得了涂层制备的较佳喷涂工艺参数。涂层为纳米结构，主要由四方相构成。     

Microstructure and Tribological Property of TiC-Mo Composite Coating Prepared by Vacuum Plasma Spraying

TiC-based composite coating using Mo as an additive has been fabricated by vacuum plasma-spraying, and then the phase composition and microstructure of TiC-Mo composite coating were investigated. Wear resistance of the TiC-Mo composite coating was comparatively studied with pure TiC coating. The experimental results showed that the microstructure of the TiC-Mo composite coating was relatively homogeneous and compact, exhibiting typical lamellar structure of plasma-sprayed coating. Orientated columnar grains of TiC can be found in the composite coating, and a (Ti, Mo)C transition phase was also observed. Due to the formation of (Ti, Mo)C transition phase, strong interface between TiC and Mo splats was obtained, which positively influenced the wear performance of the composite coating. As compared with pure TiC coating, the TiC-Mo composite coating exhibited improved wear resistance both at low and high loads. Wear mechanisms for the TiC coatings have been changed by adding Mo element.     

Microstructure and Properties Characterization of Silicon Coatings Prepared by Vacuum Plasma Spraying Technology

Silicon coatings were fabricated by vacuum plasma spraying technology. The morphology, composition, and microstructure of the coatings were investigated by FESEM, XRD, WDX, and TEM. The physical, mechanical, and thermal properties of the coatings were characterized. The results showed that vacuum plasma sprayed silicon coatings were compact and consisted of well-molten silicon splats. The oxidation introduced by the spraying process was limited. Small ball-like particles of size less than 1 μm existed both on the surface and inside of the coatings. The silicon coatings were made up of silicon grains with irregular shapes and different sizes of 0.5-1 μm. The longitudinal microstructure of silicon coatings exhibited typical two-layer microstructure of equi-axed nanometer grains and overlying columnar grains. The open porosity, density, and surface roughness of silicon coatings were 3.2%, 2.24 g/cm³, and 3.47 μm, respectively. And the microhardness and bonding strength of silicon coating, respectively, were 7.0 GPa and 20.6 MPa.     

碳化硼陶瓷活化烧结技术进展

从细化原料粉末颗粒、添加烧结助剂等方面介绍了碳化硼陶瓷活化烧结方法,分析了各种方法促进制品烧结致密化的机制,讨论了各种活化烧结方法对制品的组织和性能的影响,比较了各种方法的优缺点。并简单介绍了热压和热等静压强化碳化硼烧结的效果。     

Manufacturing Process of Nanostructured Alumina Coatings by Suspension Plasma Spraying

This paper describes the formation process of nanostructured alumina coatings and the injection system obtained by suspension plasma spraying (SPS), an alternative to the atmospheric plasma spraying technique in which the material feedstock is a suspension of the nanopowder to be sprayed. The nanoscale alumina powders (d ≈ 20 nm) were dispersed in distilled water or ethanol and injected by a peristaltic pump into plasma under atmospheric conditions. Optical microscopy (OM), scanning electron microscopy (SEM), and x-ray diffraction (XRD) analyses were performed to study the microstructure of the nanostructured alumina coatings. The results showed that the nanoscale alumina powders in suspension were very easily adsorbed at the inner surface of injection, which caused the needle to jam. The rotation of the pump had a great effect on the suspension injection in the plasma. The very small resistance of the thin plasma boundary layer near the substrate can drastically decrease the impacting velocity of nanosize droplets. The concentration of suspension also has a significant influence on the distribution of the size of the droplet, the enthalpy needed for spraying suspension, and the roughness of the coating surface. The phase structures of alumina suspension coatings strongly depend on the plasma spraying distance. A significant nanostructured fine alumina coating was obtained in some areas when ethanol was used as a solvent. The microstructures of the coating were observed as a function of the solvent and the spraying parameters.     

等离子喷涂工艺与设备的微机测控系统

以AT89C52单片机为核心,配合模数转换模块、数模转换模块、键盘模块、开关量输出模块和液晶显示模块实现等离子喷涂设备工艺参数的集中控制与检测。设备小,功能多,运行稳定,充分发挥了51单片机的潜能。本文在对系统各部分进行了阐述的同时,着重介绍了系统的人机界面和为了保障系统在恶劣条件下稳定运行而采取的抗干扰措施。     

Rapidly Solidified Thick Nickel Base Alloy Deposit with Carbide Particles Produced by Plasma Spraying

Ni-1.5 wt.% C, Ni-1.5 wt.%C-14 wt.%Cr, and Ni-1.5 wt.%C-29 wt.%Cr alloy powders were low-pressure plasma sprayed to produce nickel-base composite deposits with dispersed carbide particles. The constituent of the as-sprayed deposit formed on a water-cooled substrate from the Ni-1.5 wt.%C alloy powder is a nickel phase that is supersaturated with carbon. The deposit heat-treated at 673 K in vacuum consists of a nickel phase, nickel carbide, and graphite. In the case of the Ni-1.5 wt.%C-14 wt.%Cr alloy powder, the as-sprayed deposit produced on a water-cooled substrate is made up of a nickel phase that is supersaturated with chromium and carbon, and subsequent heat-treatment of the deposit leads to the formation of chromium carbide and graphite. When the non-cooled substrate is used, the as-sprayed deposit consists of a nickel phase, chromium carbide, and graphite. The as-sprayed deposit formed on a non-cooled substrate from the Ni-1.5 wt.%C-29 wt.%Cr alloy powder is composed of a nickel phase, chromium carbide, and graphite.     

SiC Coatings for Carbon/Carbon Composites Fabricated by Vacuum Plasma Spraying Technology

SiC coatings for carbon/carbon (C/C) composites have been prepared by the combination process of vacuum plasma spraying technology and heat treatment. The SiC coatings were formed by the reaction of C/C substrates with as-sprayed silicon coatings deposited by vacuum plasma spraying. The preparation temperature and the thickness of original silicon coatings have great influence on the microstructure and the thickness of the synthesized SiC coatings. The results indicated that a continuous and dense SiC coating has been produced on the surface of C/C substrates. The SiC coatings prepared at 2073 K with the silicon coatings of 230 μm thickness, exhibited a low mass loss of 2.56% in the plasma jet with temperature about 2473 K and duration of 420 s in atmosphere. The present results implied that vacuum plasma spraying technology combined with heat treatment was an acceptable method for synthesis of protective SiC coatings for C/C composites.     

Microstructure Characteristics and Oxidation Behavior of Molybdenum Disilicide Coatings Prepared by Vacuum Plasma Spraying

In this study, molybdenum disilicide (MoSi₂) coatings were fabricated by vacuum plasma spraying technology. Their morphology, composition, and microstructure characteristics were intensively investigated. The oxidation behavior of MoSi₂ coatings was also explored. The results show that the MoSi₂ coatings are compact with porosity less than 5%. Their microstructure exhibits typical lamellar character and is mainly composed of tetragonal and hexagonal MoSi₂ phases. A small amount of tetragonal Mo₅Si₃ phase is randomly distributed in the MoSi₂ matrix. A rapid weight gain is found between 300 and 800 °C. The MoSi₂ coatings exhibit excellent oxidation-resistant properties at temperatures between 1300 and 1500 °C, which results from the continuous dense glassy SiO₂ film formed on their surface. A thick layer composed of Mo₅Si₃ is found to be present under the SiO₂ film for the MoSi₂ coatings treated at 1700 °C, suggesting that the phenomenon of continuous oxidation took place.     

等离子喷涂陶瓷螺杆的软仿型工艺的研究

提出以软仿型加工方法实现陶瓷螺杆等离子喷涂,该方法以螺杆螺距为仿型参数,实现数控位移,以软仿型方式实现螺杆表面喷涂.探讨了该方法的工艺原理和实现技术途径,研究结果表明采用该方法有助于提高陶瓷螺杆的喷涂效率.     

等离子喷涂AlSi-ployester封严涂层工艺优化研究

采用AlSi-ployester粉末和PARXAIR-3710等离子喷涂系统制备封严涂层.为使AlSi-ployester等离子喷涂涂层获得优良的涂层性能,选择涂层结合强度为判据,通过正交试验对AlSi-ployester等离子喷涂工艺进行了优化.利用扫描电镜,Axio lmager.A lm金相图像分析系统等手段对涂层形貌和孔隙率进行分析,同时对涂层的硬度、抗热震性能进行了测试.确定优化后的工艺参数为:电弧电流790A.主气流量62.7 L/min,辅气流量5 L/min,喷涂距离100mm.结果表明,电弧电流、主气流量、辅气流量、喷涂距离对AlSi-ployester涂层结合强度具有不同的影响,在优化的喷涂工艺参数条件下,AlSi-ployester涂层结合强度可达6.9MPa,具有较好的硬度和热震性能,可为今后等离子喷涂系统工艺参数的选定提供参考.     

碳化硼涂层材料研究进展

综述了碳化硼材料的基本结构、主要性能参数、各种制备碳化硼涂层的方法以及碳化硼涂层的应用现状和前景。讨论了物理气相沉积、化学气相沉积、等离子喷涂、气体转换、反应一烧结、等离子浸没离子处理等方法和涂层的性能特点。碳化硼涂层要在众多领域获得广泛应用,如何制备更均匀致密的碳化硼涂层、提高涂层与基体之间的结合力、降低涂层应力仍是今后研究的重点。     

Plasma Spraying of Metal Coatings Using CO2-Based Gas Mixtures

Compared to argon, plasmas generated by molecular gases and operated at the same electric current level contain much higher enthalpy. This is because molecular gases must dissociate before ionization, which requires larger energy input. The authors have developed a new DC plasma torch, which operates with a mixture of carbon dioxide (CO₂) and methane (CH₄). The torch was employed for plasma spray coating with input power in a range of 30 to 45 kW. This paper reports on the effect of CO₂/CH₄ mixtures on the particle conditions during spraying of nickel alloy powders. Results of gas composition analysis at various distances from the nozzle exit are presented. The particle in-flight conditions, coating microstructure, and deposition efficiency are analyzed.     

真空渗硼预处理在CVD金刚石-硬质合金涂层工具中的应用

采用固体粉末真空渗硼工艺,研究了硬质合金工具表面真空渗硼预处理对金刚石涂层附着力的影响,研究结果表明,硬质合金工具通过固定粉末真空渗硼处理,表面生成具有较高稳定性的以CoWB、CoB为主的渗层,经过长时间的金刚石涂层后,硬质合金工具表面出现Co3B和W2Co21B6相,没有单质Co相出现,克服了金刚石沉积中硬质合金表面钴的不利影响,使标志金刚石涂层附着力的压痕测试的临界载荷达到了1500N,并且有着较好的重现性。