金属陶瓷复合塑料切粒刀的研制及应用

研究了ＴｉＣ－ＮｉＣｒ金属陶瓷在塑料切粒刀上的应用。这种切粒刀结构特点是金属陶瓷刀刃与钢刀体通过高温真空扩散焊复合为一体。结果表明这种金属陶瓷复合切粒刀性能比钢结硬质合金切粒刀更好。     

Influence of the surface activity of sulfur on the desulfurization of metal by manganese

An improved dynamic model demonstrates that the surface activity of sulfur has a positive influence on the desulfurization of metallic melt during the solution of manganese. With 1% increase in the sulfur content at the phase boundary, desulfurization increases by 3–12%, on average. The calculations here employ relative values and assume steady conditions, without taking account of the actual surface layer thickness. In other words, these are additive calculations.     

Microstructural changes during wear by plastic deformation of cemented carbide and cermet cutting inserts

The microstructure of one WC-Co and two Ti(C,N)-WC-Co cutting inserts has been studied before and after plastic deformation, caused by high-speed turning. It was found that after deformation, the binder phase had infiltrated some of the grain boundaries and formed lamellae between the hard phase grains. The infiltration of grain boundaries was assumed to occur by a stress-induced dissolution along the grain boundaries of the hard phase grains as a wide front of binder phase, rather than gradually by Co grain boundary diffusion. Some localized dissolution of the hard phase could also be seen as faceting of grains in WC-Co and at triple points in cermets. It was concluded that the plastic deformation occurs by grain boundary infiltration with simultaneous grain boundary sliding. The rate of deformation is controlled by grain boundary infiltration through dissolution of the hard phase grains.     

金刚石辅磨料对混凝土锯片使用寿命和切割效率的影响

采用与主磨料粒度相差较大的金刚石微粉作为辅磨料,设计和制备了13种不同配方的金刚石小锯片进行切割混凝土的试验,实现主辅磨料双切削共同作用。通过混凝土切割实验和理论分析,研究金刚石辅磨料对金刚石锯片寿命和切割效率的影响。结果表明,在锯片中加入适量浓度的细颗粒金刚石作为辅磨料,能较大幅度提高混凝土金刚石锯片的切割效率及使用寿命。金刚石作为辅磨料可协助主磨料共同参与切割混凝土,能加快锯片的新陈代谢,使单位切削面上的受力点增多,且减小金刚石颗粒之间的间距,使大于金刚石间距的砂粒磨削不到胎体,从而减少砂粒对胎体的磨损,金刚石锯片的使用寿命最多可提高150%以上,切割效率提高约40%。     

线切割的电流密度对无取向电工钢切面的影响

对无取向电工钢进行电火花线切割实验,研究切割过程中不同的电流密度水平对切割面形貌的影响。采用三维测量激光显微镜对原始切割面的形貌进行观察,采用扫描电子显微镜观察经同等水平的超声振动方式处理后的切割面,以衡量表面附着层的附着能力。结果表明,随着电流密度水平的升高,切割面呈粗糙化趋势,由均匀光滑的小幅度凸起区和凹陷区逐渐替代为易于氧化的不规则台阶,台阶在高度方向的过渡区域为近垂直状;在过高的电流密度下,出现被氧化区包围的光亮近球形再凝固体。所以,高电流密度对控制切割面质量不利,采用较低电流密度的电火花线切割技术具有较高优势。