汽车用316L不锈钢激光/等离子喷涂Co-Cr3C2涂层组织与结合强度分析

为了提高汽车用316L不锈钢表面的机械强度,采用激光/等离子喷涂的方法制得Co-Cr3C2涂层,并与等离子喷涂层进行比较,试验测试分析了涂层的微观组织及沉积过程中的焰流形态。分析结果表明:采用等离子喷涂制得的涂层存在大量孔隙;利用激光/等离子喷涂制备的Co-Cr3C2涂层具有明显的冶金结合特征,涂层中的孔隙裂纹较少。以激光/等离子喷涂制备的Co-Cr3C2涂层孔隙率小于等离子喷涂层的,结合强度高。等离子喷涂形成了完全熔融、部分熔融以及没有熔融的3种颗粒;采用激光/等离子进行喷涂制得的涂层内没有产生尺寸较大的的未熔颗粒,达到了更好的铺展状态,形成了尺寸更小的晶粒,显著降低了涂层中的裂纹与孔洞数量,提高了涂层的表面硬度与耐磨性。     

粉末粒度对等离子喷涂Al2O3-13%TiO2陶瓷涂层组织结构及性能的影响

等离子喷涂粉末的粒度影响涂层组织结构与性能。选用4种不同粒度的Al2O3-13%TiO2(AT13)粉末等离子喷涂陶瓷涂层,研究了喷涂粉末粒度对涂层组织结构、孔隙率、显微硬度和沉积效率的影响。结果表明:采用较细的喷涂粉末制备的AT13涂层致密、均匀,孔隙率低;随着喷涂粉末粒度增大,涂层的孔隙率增加,显微硬度降低,沉积效率先增后减;采用粒度为38～44μm的粉末喷涂涂层时沉积效率最高,达到51%,涂层组织也较致密,这是等离子喷涂AT13陶瓷层较理想的粒度。     

轴向送粉等离子喷涂纳米氧化铬涂层的结构与性能

普通等离子喷枪外径向送粉,粉末利用率低,采用轴向送粉等离子喷涂系统在不锈钢上制备了纳米氧化铬涂层.测试了涂层的硬度及结合强度;应用SRV振动摩擦磨损试验机研究了涂层的摩擦磨损性能;通过金相、场发射扫描电子显微镜及X射线衍射对涂层的形貌及组织结构进行了研究.结果表明,与普通氧化铬涂层相比,纳米氧化铬涂层的硬度及结合强度更高、摩擦系数更低、抗摩擦磨损性能更好.     

等离子喷涂制备ZrB2-MoSi2复合涂层及其抗氧化性能

采用喷雾干燥与真空烧结技术制备出不同MoSi₂含量的ZrB₂-MoSi₂球形团聚粉末, 并以平均粒径为30 μm的ZrB₂-MoSi₂团聚粉末为原料, 利用大气等离子喷涂法在C/C复合材料表面制备包覆完整的ZrB₂-MoSi₂复合涂层, 借助XRD、SEM等对涂层的组织结构以及涂层的抗氧化性能进行了研究。结果表明: ZrB₂-MoSi₂涂层结构均匀致密, 结合强度达到7.2 MPa。适当含量的MoSi₂, 可以提高涂层的抗高温氧化性能; ZrB₂-40wt%MoSi₂涂层C/C复合材料试样在1500℃静态空气中氧化9 h, 失重率仅为1.7%, 涂层具有良好的自愈合能力, 表现出优异的抗高温氧化性能。     

气流粉碎B4C粉末的掺碳活化烧结研究

开展了气流粉碎B₄C粉末(比表面积2.53m²/g)的掺碳烧结实验,研究了掺碳剂种类、掺碳量、烧结温度、比表面积等对B₄C烧结密度的影响。结果表明,掺碳显著促进B₄C的烧结;在炭黑、葡萄糖和酚醛树酯三种掺碳剂中,掺入酚醛树酯可以获得最高的烧结密度;并且最佳的掺碳量为3％～5％C,B₄C+3％C(酚醛树酯)分别经2200和2250℃烧结后的密度为92.1％TD和94.4％TD,若采用振动球磨B₄C粉末(8.30m²/g)进行掺碳烧结实验,则可使2200℃的烧结密度提高到95.6％TD。     

等离子喷涂纳米莫来石基复合吸波涂层性能研究

应用喷雾造粒技术制备了Mg₃Si₄O₁₀(OH)₂、C与莫来石复合吸波粉末, 并采用等离子喷涂技术制备了复合吸波涂层. 在涂层沉积过程中, 吸收剂相的C发生反应, 滑石相高温氧化、分解, 生成原顽辉石. 实验结果表明, 结合强度随涂层厚度增加而降低, 0.8mm时达到2MPa. 并用小波分析方法得出涂层断裂源为晶界玻璃相. 涂层中新生成相的成分增加了涂层的介质损耗性能, 使得涂层的电磁波反射性能下降, 并向高频部分偏移, 随涂层厚度的增加, 反射率曲线向低频移动, 所制备涂层在0.8mm时在15～18GHz之间均小于-5dB.     

由聚碳硅烷生成纳米SiC颗粒增强B4C基复相陶瓷的结构与性能

制备了由聚碳硅烷（PCS）为先驱体裂解形成的纳米SiC增强的B₄C基复合材料,并与直接球磨混合法制备的纳米SiC增强的B₄C基复合材料进行了对比研究.实验结果表明,先驱体法制备的复合材料形成一种复杂的晶内/晶间结构;B₄C内部的纳米SiC和Al₂O₃内部的少量纳米SiC、晶界处的层片状SiC、B₄C晶粒内部的SiC亚晶界结构.材料的断裂方式以穿晶断裂为主,形成晶内裂纹扩展路径,增强了材料的韧性.采用PCS为先驱体工艺制备高性能的纳米复相陶瓷,其组织均匀性、致密度和力学性能均优于直接机械混合制备的纳米复合材料.     

超音速等离子喷涂制备水力机械耐冲蚀涂层的研究

SQC-100新型超音速等离子喷涂系统既有HVOF的高速度和涂层致密性,又有等离子的高沉积效率,能够在保证涂层质量的前提下有效降低成本。采用SQC-100型超音速等离子喷涂技术喷涂WC-10Co-4Cr涂层,并研究其耐冲蚀性能。结果表明,孔隙率为0.77%,硬度为1 210HV0.2,结合强度达到72 MPa,涂层性能基本达到超音速火焰喷涂同等水平。此外,获得的涂层具有良好的耐泥沙冲蚀性能,涂层耐冲蚀性是ZG0Cr13Ni4Mo不锈钢的3.88倍,并研究了涂层内部裂纹主要以穿晶断裂形式扩展。研究表明WC-10Co-4Cr涂层在高含沙水流中的水力机械零部件领域有广泛的应用前景。     

等离子喷涂氧化锆纳米涂层显微结构研究

利用大气等离子喷涂（APS）技术,在不锈钢基体上制备了氧化锆纳米结构涂层.运用XRD、SEM与TEM等分析手段对喷涂用粉末原料和涂层的显微结构、物相组成进行了观察和确定.实验结果表明,纳米氧化锆粉末经喷雾造粒后的颗粒粒径主要分布在15～40μm之间,流动性好,适合于等离子喷涂用.等离子喷涂氧化锆纳米涂层颗粒分布在60～120nm之间,晶粒发育良好.涂层物相由四方和立方相氧化锆所组成.氧化锆纳米涂层的气孔率约为7％,结合强度为45MPa。     

二硅化钼喷涂粉末的制备及其涂层组织结构

以粒度为1~2μm的MoSi₂粉末为原料,采用喷雾干燥和真空烧结制备了喷涂用MoSi₂团聚粉末. 分别用平均粒度为9.68μm的MoSi₂粉末和团聚造粒MoSi₂粉末(38~72μm)为喂料, 大气等离子喷涂制备了二硅化钼涂层,分析了涂层的微观组织结构. 研究结果表明,喷雾干燥造粒后的近球形粉末在1300℃真空烧结1h后,粉末流动性和松装密度分别为17.1s/50g和2.16g/cm³,比烧结前分别增加了57.0%和46.0%.平均粒度为9.68μm 的MoSi₂粉末制备的涂层主要是由Mo和Mo₅Si₃等富钼相组成. 团聚粉末制备的涂层主要由MoSi₂相组成,涂层较致密, 内部出现了类似“网状”的组织结构.     

Corrosion properties of titanium based hard coatings on steel

Titanium nitride TiN, titanium boronitride Ti(B,N) and titanium carbonitride Ti(C,N) coatings were deposited by PA-CVD on tempering and stainless steel substrates. The deposition process can be supervised by OES. The coatings were characterized XRD, SEM and WDS as well as hardness, adhesion and friction tests. Electrochemical impedance measurements and cyclic voltammetry in praxis relevant media were carried out. Mechanical and corrosion properties of the coatings can be controlled by the PA-CVD process parameters. The incorporation of chlorine in the coating can be varied by the process parameters with TiCl₄ or completely avoided using metallo-organic precursors. No influence of the chlorine content on the corrosion behavior was observed. Even coatings with extremely high chlorine content still exhibit an excellent corrosion resistance. Thus, the microstructure of the coating is the key to the corrosion properties of hard coatings on steel. A new micro electrochemical scanning droplet technique with a lateral resolution of 150 μm allows the investigation of TiN-coated substrates of complex geometry. The PA-CVD technique permits the deposition of dense and pinhole free coatings. On structures with simulated aspect ratios less than 3, a dense protective coating is proved. However, if the formation of micro pores is not suppressed by the optimal choice of deposition parameters, low-alloyed steel substrates corrode through pores, causing a detachment of the coating. On layers deposited on stainless steel, no sign of substrate corrosion could be detected. A model for the corrosion mechanism is given in Fig. 17.     

等离子喷涂 AP40生物活性玻璃陶瓷涂层的结构和性能

采用大气等离子喷涂技术，在TiA16V4基体上制备了AP40玻璃陶瓷涂层．利用光学显微镜、SEM和XRD分析技术对涂层形貌、显微组织结构和相组成进行了研究．探讨了热处理工艺对涂层组织结构及其性能的影响，并按德国DIN 50160标准进行涂层的拉伸强度试验．结果表明：等离子喷涂AP40玻璃陶瓷涂层在喷涂态，只有较低的结晶度．喷涂工艺对涂层的孔隙率和粉末沉积率有较大的影响．合适的热处理工艺可提高涂层的结晶度，减少孔隙以及提高结合强度．     

Composite ceramic-metal coatings by means of combined electrophoretic deposition and galvanic methods

A method based on the combination of electrophoretic and galvanic deposition techniques has been developed to fabricate metal-ceramic composite coatings on metallic substrates. A ZrO₂-Ni composite coating with interpenetrating microstructure was produced on stainless steel plates. For electrophoretic deposition of the ceramic component, a non-aqueous suspension consisting of zirconia nanoparticles, ethanol and addition of 4-hydroxybenzoic acid was optimised by electrokinetic sonic amplitude (ESA) measurements. The zirconia deposits were partially sintered to create an open porous structure (porosity = 40–50%), which was subsequently filled with Ni by galvanic deposition. The bonding strength between the composite coating and the stainless steel substrate was improved by a final heat-treatement at 950°C for 3 h which promoted the diffusion of Ni into the steel substrate and the formation of a diffusion interlayer. The high adhesion strength of the composite coating to the stainless steel substrate after the diffusion bonding heat-treatment was confirmed by 3-point flexural strength tests. The coating exhibited a homogeneous interpenetrating microstructure with hardness values >6 GPa.     

Influence of Gas Temperature on Microstructure and Properties of Cold Spray 304SS Coating

In the present study, 304 stainless steel coatings were deposited on interstitial-free steel substrates by cold gas dynamic spray technology. The effect of gas temperature on microstructure, micro-hardness, cohesive strength, and electrochemical property of the coatings were investigated and compared. The results showed that increasing gas temperature had a great contribution to enhancing the bonding strength between the deposited particles and making the microstructure more density. Therefore, the porosity of the coatings decreased from 6%±0.5% to 2%±0.3%, and the tensile strength of the coatings increased from 56±4 MPa up to 73±3 MPa. In addition, the corrosion resistance of the coatings was also deeply influenced by process gas temperature. The corrosion kinetics of the coatings were affected by both of the plastic deformation of deposited particles and the porosity in the coatings.     

激光辅助冷喷涂制备高硬度材料涂层的研究进展

冷喷涂是一种新型的低温固态涂层制备技术,在制备温度敏感、相变敏感、氧化敏感材料涂层方面表现出突出的优势。但单纯冷喷涂技术无法沉积高硬度材料,这极大地限制了冷喷涂的应用范围,为了解决该问题,激光技术被引入冷喷涂沉积过程中同步软化喷涂颗粒与基板,这不仅能使高硬度材料实现有效沉积,还能提高冷喷涂涂层的沉积效率、致密度和结合强度等,拓宽冷喷涂沉积材料的选择范围。阐述了激光辅助冷喷涂技术的原理、特点和优势,综述了该技术在沉积制备高硬度金属及金属基耐磨复合涂层的国内外研究现状。     

纳米TiO_2-WO_3复合涂层及纳米TiO_2/WO_3叠层涂层的制备及性能

为了解决电子池材料改性TiO2涂层暗态下无阴极保护作用的问题,用溶胶-凝胶法及浸渍提拉技术在304不锈钢表面制备了纳米TiO2-WO3复合涂层与纳米TiO2/WO3叠层涂层,用扫描电镜(SEM)、X射线光电子能谱仪(XPS)研究了2种涂层的表面形貌、成分,并用电化学方法研究了2种涂层的光阴极保护特性及耐腐蚀性能。结果表明:2种涂层表面均连续均匀,由Ti,W,O,C组成;紫外光照1 h时2种涂层均对304不锈钢有一定的光阴极保护作用,闭光后纳米TiO2/WO3叠层涂层的延时阴极保护作用远好于纳米TiO2-WO3复合涂层;2种涂层均对304不锈钢有防腐蚀作用,紫外光照射时纳米TiO2-WO3复合涂层的防腐蚀性比纳米TiO2/WO3叠层涂层的好。     

超级铁素体不锈钢表面超疏水结构的制备及其耐腐蚀性能

将多巴胺的自发聚合反应与低表面能物质ODA和PFDT结合,在超级铁素体不锈钢表面制备了均匀致密的超疏水薄膜。用水雾凝聚实验、扫描电子显微镜(SEM)和X射线能谱分析(EDS)等手段表征了涂层修饰前后的润湿性、表面形貌以及化学结构,并使用三电极体系电化学工作站测试了超级铁素体不锈钢表面修饰前后涂层的阻抗谱和极化曲线。结果表明：修饰前超级铁素体不锈钢涂层表现为亲水性,修饰后表面有超疏水薄膜的超级铁素体不锈钢具有更低的腐蚀电流密度和更高的涂层电阻,修饰处理能明显提高超级铁素体不锈钢涂层的防腐蚀性。在涂层表面形成的超疏水膜具有“微纳米结构空气谷”,阻碍了强腐蚀性氯离子在溶液与固体界面间的扩散和迁移界面电化学反应腐蚀产物的脱落与溶解,提高了电荷转移电阻,降低了电流腐蚀密度,从而提高了涂层的防腐蚀性。     

40Cr钢表面涂敷层的磨损和腐蚀磨损研究

用掺有 10 %(w)CeO2 粉末的及未掺的KF 2 0 1铁基高强度耐磨合金粉末 ,对淬火态 40Cr钢材表面进行喷涂、喷熔和激光涂敷等表面处理 ,考察了用这 3种工艺制作的 6种涂层的显微组织、硬度分布、无润滑磨损和腐蚀磨损。结果表明 ,涂层的磨损抗力和腐蚀磨损抗力都比 40Cr钢基底的大为提高。激光涂敷层的磨损抗力达到淬火态 40Cr钢基底的 5倍以上 ,在 5 %盐水 +石英砂内进行腐蚀磨损试验 ,激光涂敷层的腐蚀磨损抗力达到 40Cr钢基底的 2倍以上。在KF 2 0 1粉末中掺入CeO2 ,Ce能使涂层组织细化 ,涂层磨损抗力与腐蚀磨损抗力得到进一步的提高。     

低压等离子喷涂316L等轴晶涂层及其性能研究

为研究低压等离子喷涂等轴晶涂层组织性能和形成机理,采用大气等离子喷涂（APS）和低压等离子喷涂（LPPS）,分别制备了316L不锈钢涂层.利用金相显微镜,X射线衍射和显微硬度等方法,分析了2种涂层的金相组织、相结构、显微硬度和耐蚀性.结果表明：一定条件下制备的低压等离子喷涂SUS316L不锈钢涂层明显不同于传统大气等离...     

Characterization and comparison between APS coatings prepared from ball milled and plasma processed nickel–aluminium powders

Plasma spraying has wide range of applications which include corrosion, thermal and abrasion resistance coatings. In the present work, nickel and aluminium powders were ball milled and the same were thermal plasma processed to produce spherical nickel alumindes particles. Both ball milled and plasma processed powders were spray deposited on stainless steel (SS 304) substrate using atmospheric plasma spray technique (APS). The experiments were carried out for different plasma input power levels, torch to base distances and coating thicknesses. Microstructure, micro hardness, adhesive strength, and porosity of the coatings are reported and discussed. Effect of plasma processing parameters and plasma spheroidization of powders on coating properties has been evaluated and reported. High plasma power, low torch to base distance lead to high temperature supplied to in-flight particles which correspond to high hardness, low porosity and high adhesion. Spherical morphology and formation of nickel aluminide intermetallic were achieved by plasma spheroidization. Coatings prepared from plasma processed powders enhance the coating properties positively.