YT类硬质合金成形铣刀的金刚石涂层工艺研究

针对YT15硬质合金B212型成形铣刀片,以两种不同的化学方式对硬质合金基体进行预处理,而后采用热丝化学气相沉积的方法在其表面沉积微米级金刚石薄膜.使用扫描电子显微镜观察金刚石薄膜颗粒的大小及均匀度,激光拉曼光谱仪检测金刚石涂层的成分,压痕法检验金刚石涂层刀片的膜-基附着强度,并就不同预处理的基体表面对金刚石薄膜的质量、附着性能的影响进行分析.结果表明,经预处理后的YT类硬质合金表面粗糙度较YG类降低约10%,采用平行布置热丝方式和现有的沉积工艺在YT类硬质合金衬底涂覆的金刚石薄膜均匀性较好,且经酸碱预处理的金刚石薄膜表现出良好的附着力,附着强度介于600~1 000 N,醇碱预处理对衬底表面原有的光洁度损坏较小,有助于细化金刚石晶粒,但膜-基附着强度不高.     

Mierostrueture and Properties of Coating from Cemented Carbide on Surface of H13 Steel

The microstructures and properties of coating from cemented carbide on the substrate of H 13 by vacuum powder sintering were studied. The effect of sintering temperature on the microstructures of coating was discussed. The interface characteristics between coating and H 13 steel substrate, microhardness distribution and wear resistance in the coating were analyzed. The coating from cemented carbide with thickness of 1-3 mm by vacuum powder sintering at temperature ranging from 1280℃to 1300 ℃ was obtained. The experimental results indicated that the coating with microhardness of HV 1600 favorable to wear resistance is strongly bonded with the H 13 steel substrate by mutual diffusion and penetration of Fe,Cr, Mo,V in substrate towards the coating and W, Co,Ni in coating towards the substrate.     

Preparation of bioactive calcium phosphate coating on porous C/C substrate by a novel deposition technique

A novel heat substrate technique, high frequency inductive heat deposition （IHD）, was introduced to coat porous carbon materials, C/C and carbon felt to improve their bioactivity. The morphologies, composition and microstructure of the resulting coatings were examined by scanning electron microscopy （SEM）, energy dispersive spectra （EDS）, X-ray diffractometer （XRD） and Fourier transform infrared spectroscopy （FTIR）. The results show that, the calcium phosphate consisted of non-stoichiometric, CO3-containing and plate- like octacalcium phosphate （Ca8-xH2（PO4）6, OCP） could uniformly cover the entire porous surfaces of carbon materials. Good adhesion of the coating to carbon material substrates was observed.     

真空热处理对热障涂层组织形貌及元素扩散的影响

为了研究真空热处理对CoNiCrAlY涂层组织形貌及元素扩散的影响,采用超音速火焰喷涂(HVOF)设备在镍基高温合金基体上制备了CoNiCrAlY涂层.对部分样品进行真空热处理,利用大气等离子喷涂8YSZ陶瓷层.采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能谱分散谱仪(EDS)等分析了热障涂层的相组成、微观组织、元素扩散与热震性能,研究了真空热处理对热障涂层的影响.结果表明,真空热处理后,CoNiCrAlY涂层颗粒间界面消失且涂层发生均质化;涂层与基体界面处元素发生扩散;热障涂层的抗热震性能提高.     

TA1表面制备Ni/Al涂层的反应扩渗及抗氧化行为

为了提高纯钛的高温抗氧化性能,采用电弧喷涂和等离子喷涂方法在纯钛表面制备Ni/Al涂层.对试件进行900 ℃×5 h热处理后,再进行900 ℃×40 h连续氧化实验,探索其高温抗氧化行为.结果表明,经过表面改性处理的Ni/Al涂层可以显著提高纯钛的高温抗氧化性.在热处理过程中Ni/Al涂层中的Al发生熔化扩散并与Ni和Ti形成以NiAl与TiAl₃相为主的扩散层.在氧化过程中Ni/Al涂层表面形成连续且致密的α-Al₂O₃,同时表面扩散层中的富铝相可为涂层表面提供充足的Al元素,进而对纯钛基体提供有效的高温抗氧化保护作用.     

2738模具钢表面激光熔覆Ni基WC复合涂层的摩擦磨损性能

在2738模具钢表面通过CO2激光熔覆制备Ni基WC复合涂层。分别对2738钢基体和Ni-WC激光熔覆层进行干摩擦试验。用三维表面形貌仪测量磨损体积,用扫描电镜观察磨痕的表面形貌。试验结果表明,Ni-WC复合涂层试样的硬度显著提高,表面硬度超过1200HV,保证了Ni-WC熔覆层的耐磨性。熔覆层的平均摩擦因数约为0.24,与2738钢基体的摩擦因数0.43相比,降低了约44%。熔覆试样的比磨损率比基体试样的比磨损率下降了96.7%,WC硬质相提高了摩擦副表面的承载能力。磨粒磨损为Ni-WC复合涂层的主要磨损机理。     

<Emphasis Type="Italic">In-situ</Emphasis> synthesis and characteristics of TiC−Fe cermet graded composite coating on a steel substrate

By means of an inherent elevated-temperature of poured liquid steel, a Ti-C-30 wt% Fe preform, which was pre-placed in a mould cavity, was directly ignited and a combustion synthesis reaction took place. As a result, a TiC−Fe cermet coating with a thickness of about 10 mm was simutaneously synthesized on the solidified steel matrix. The synthesized coating exhibits a feature of graded composite structure, in which both the amount and size of TiC particles decrease gradually with an increasing distance from the furface of the coating. Moreover, by a proper casting technique, the pores formed during the combustion synthesis of the preform could be centrally distributed in 2–3 mm in outer layer of the coating. When this outer porous layer was worn off, the rest coating with a thickness of about 8 mm possesses a dense structure and a high abrasive wear resistance. YAN You-wei Born in 1965 Financially supported by the National Natural Science Foundation of China (No. 50276023)