激光熔覆Al2O3+TiO2复合陶瓷涂层的微观结构

研究了４５＃钢表面Ａｌ２Ｏ３＋ＴｉＯ２复合陶瓷激光熔覆层的微观组织和相结构、Ａｌ２Ｏ３＋ＴｉＯ２复合陶瓷激光熔覆涂层由α－Ａｌ２Ｏ３,ＴｉＯ２,γ－ＴｉＯ２,γ－Ａｌ２Ｏ３及Ａｌ２ＴｉＯ５相组成,消除了等离子喷涂层的层状组织特征,形成了大致方向的柱状晶,晶内为溶入了Ｔｉ及少量底层元素的α－Ａｌ２Ｏ３;晶界为由ＴｉＯ２和Ａｌ２Ｏ３形成的Ａｌ２ＴｉＯ５相,溶有少量的Ｃｒ,Ｆｅ,Ｙ取代了Ａｌ２ＴｉＯ５     

W18Cr4V钢表面激光熔覆Al2O3陶瓷涂层的组织结构

研究了Ｗ１８Ｃｒ４Ｖ钢表面Ａｌ２Ｏ３／ＮｉＣｒＡｌ复合陶瓷涂层的组织结构、成分分布及界面组织特征。结果表明：Ａｌ２Ｏ３／ＮｉＣｒＡｌ复合陶瓷等离子喷涂层的组织呈层片状,面层由α－Ａｌ２Ｏ３和少量的γ－Ａｌ２Ｏ３组成,层间为机械结合界面,界面处成分变化梯度较大。经激光重熔后的面层组织为单一的α－Ａｌ２Ｏ３柱状晶,Ａｌ２Ｏ３与中间合金ＮｉＣｒＡｌ间存在明显的界面反应,且界面相增多,在ＮｉＣｒＡｌ与基体     

激光熔覆Ni包WC复合涂层的组织、耐磨和耐蚀性分析及应用

对45钢基体进行激光熔覆Ni包WC金属陶瓷涂层强化处理,通过X射线衍射(XRD)、扫描电子显微镜-能谱分析(SEM-EDX)和透射电子显微镜(TEM),研究了激光熔履Ni包WC涂层的显微组织和物相组成,并采用摩擦磨损试验和电化学测试系统研究了Ni包WC涂层的摩擦磨损性能和耐蚀性能.结果表明,在激光熔覆Ni包WC金属陶瓷...     

La_2O_3对激光熔覆生物陶瓷涂层显微组织结构的影响

采用梯度激光熔覆技术在钛合金(TC4)基体表面制备生物陶瓷涂层,研究不同含量稀土氧化物La2O3的加入对生物陶瓷涂层显微组织结构的影响。结果表明,La2O3对合成HA和β-TCP具有明显的催化作用,在生物陶瓷涂层表面形成了白色球形颗粒状的类珊瑚状结构,涂层与基体实现了良好的冶金结合。     

激光熔覆原位合成TiC-TiB2/Ni基金属陶瓷涂层的组织和摩擦磨损性能

采用激光熔覆技术,以NiCrBSiC预合金粉末为原料,在TC4合金表面制备出以原位合成的TiC和TiB2颗粒为增强相的Ni基金属陶瓷涂层。测试了涂层的显微硬度。利用销-盘式摩擦磨损试验机,以YG8B硬质合金为对磨偶件(盘),评价了涂层的干滑动摩擦磨损性能。结果表明:涂层的硬度Hv为900～1100,摩擦系数为0.2～0.3,质量磨损率比TC4合金降低约1个数量级。     

Microstructure and high-temperature resistance of Al2O3/CoNiCrAlY coatings by laser cladding

This work reports on systematic investigation of the microstructure and oxidation behavior of Al₂O₃/CoNiCrAlY coatings in-situ synthesized on a K438 nickel-based superalloy substrate via laser cladding. Scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction were used to evaluate the microstructure evolution, phase transition and high-temperature resistance. Results indicated that, as the Al₂O₃ fractions increased from 0 to 25 wt%, the average grain size of CoNiCrAlY-xAl₂O₃ coatings decreased from ∼100.23 μm to ∼42.56 μm, and the high-temperature resistance was effectively improved due to the formation of (Co,Ni)(Al,Cr)₂O₄. However, the other deleterious effect that shielding layers easily to be exfoliated with the excessive formation of (Co,Ni)(Al,Cr)₂O₄, caused a degradation in high-temperature resistance.     

ICP-AES同时测定硼铁中铝、磷、镍、铜、钛和钒

硼铁试样采用微波消解法进行试样前处理工作,电感耦合等离子体光谱仪测定硼铁中铝、磷、镍、铜、钛和钒等6种元素,优化了仪器参数,并选择了最佳谱线进行测定,同时对曲线进行基体匹配,克服了基体效应的影响,本方法具有良好的精密度和准确度,回收率在95%～110%之间,RSD均小于4%,能够满足日常生产分析中对硼铁测定的需要。     

Regulation mechanism of in-situ synthesized (Nb,Ta)C/Ni composite cladding coatings by laser shock peening: Microstructure evolution and electrochemical corrosion behavior

The surface microstructure of (Nb,Ta)C/Ni composite cladding coatings containing in-situ synthesized composite carbides (ISSCC-LCed coatings) was regulated by laser shock peening (LSP). The regulation mechanism of laser shock waves (LSW) on the microstructure evolution and electrochemical corrosion behavior of the ISSCC-LCed coatings was emphatically revealed. Correspondence between corrosion morphology and microstructure was established. Meanwhile, the phase evolution and residual stress variation laws were also tested and analyzed. The obtained results indicated that the LSW-induced surface structure exhibited interphase distribution characteristics of large and small grains through plastic deformation mechanisms such as extrusion, slip, folding, fracture, and cracking. Plastic deformation caused the relative movement of (Nb,Ta)C at the subsurface out of the surface, and the large (Nb,Ta)C fractured and extended over the entire carbide. Furthermore, element interdiffusion phenomenon existed between (Nb,Ta)C and Fe–Ni alloy. The coupling effect of LSW-induced surface fine grains and residual compressive stress inhibited corrosion propagation and improved electrochemical corrosion resistance.     

Effects of heat treatment on microstructure and mechanical properties of TiC/TiB composite bioinert ceramic coatings in-situ synthesized by laser cladding on Ti6Al4V

To improve the wear resistance of titanium alloy, in this work, TiC/TiB composite bioinert ceramic coatings were synthesized in-situ via laser cladding using Ti and B₄C mixed powders as precursor materials. And to decrease the impact of the excessive residual tensile stress generated by the uneven temperature distribution on the performance of coatings, the coatings were then subsequently heated for 3 h at different temperatures (400 °C, 600 °C, and 800 °C) and then air cooled. The effects of heat treatment on the microstructure, residual stress, micro-hardness, fracture toughness, and wear resistance of the coatings were investigated. The results showed that phase compositions and microstructure of the heat-treated coatings were virtually identical to that of the untreated coatings; however, the precipitation of acicular TiB enhanced mechanical properties of the heat-treated coatings. In addition, the average residual tensile stress values of the coatings decreased as the heat treatment temperature increased, which improved fracture toughness of the coatings from 3.95 to 4.68 MPa m^1/2. Moreover, wear resistance of the coatings was greatly enhanced by heat treatment; as the wear volume of the heat-treated coatings decreased by 50% at 800 °C compared with that of the untreated coatings. Lastly, the coatings showed good biocompatibility after being evaluated in vitro, and therefore had broad application prospects in the field of orthopedic implants.