Ni-A1掺杂WC粉末激光燃烧合成复合材料组织性能研究

采用高能束激光诱发自蔓延原位自生反应合成金属陶瓷颗粒增强复合材料的方法,通过对掺杂不同含量WC粉末的Ni-Al粉末压坯进行激光点燃自蔓延烧结,制备硬质颗粒增强NiAl基复合材料。得到了烧结合金的XRD、OM、显微硬度、摩擦磨损测试等结果。结果表明：未添加WC粉末时,烧结合金物相有Ni3Al,NiAl,Al2O3相,当加入WC时,新添了WC以及Ni4W和WO3相;加入WC后组织晶粒更加均匀、细化,呈细小的胞状;当WC粉末质量分数为1％时,相对密度最大为6．864g／cm3,孔隙率最低为0．189％;WC的添加能增加材料的力学性能,且当添加量为1％时,硬度最高为687．3HV,其磨损率最低为0．309mg／mm^2。     

WC粒度对超音速火焰喷涂WC-10Co-4Cr涂层耐腐蚀性能的影响

采用制粒?高温快速烧结法制备两种分别含亚微米级和微米级WC粒径的WC-10Co-4Cr喷涂粉末,并用超音速火焰喷涂(HVOF)技术在45#钢基体上制备涂层;利用扫描电子显微镜和电化学工作站分别对涂层的显微形貌及耐腐蚀性能进行分析检测,探讨WC粒度对涂层耐腐蚀性能的影响和涂层的电化学腐蚀机理。研究结果表明：两种涂层组织致密,界面结合良好;含亚微米级WC粒径的涂层具有相对较低的孔隙率,使其涂层的耐腐蚀性能优于含微米级WC粒径的涂层。在3.5%NaCl溶液中涂层的硬质相WC和粘结相Co发生电偶腐蚀,且低电位的Co相优先腐蚀,导致WC颗粒脱落,出现凹坑及点蚀现象。     

热处理态钢结硬质合金WC相析出微结构分析

利用SEM研究了热处理后钢结硬质合金TLMW50复式碳化物中WC相的析出及其微结构.结果表明:经过1100℃淬火后烧结态钢结硬质合金TLMW50中主要复式碳化物Fe3W3C、Fe2W2C相发生析出分解.三角状、菱形状WC相颗粒随机分布在Fe3W3C、Fe2W2C相颗粒上.淬火二次析出WC相颗粒有利于提高烧结态钢结硬质合...     

机械合金化制备纳米WC硬质合金粉的研究

综述了机械合金化的原理、设备和特性。论述了用机械合金化技术制备纳米WC硬质合金粉的影响因素。     

硬质相粒度对金属陶瓷断裂韧性的影响

用压痕法测定了具有不同粒度硬质相的Ti(C,N)基和WC基金属陶瓷的断裂韧性,结果发现,Ti(C,N)基金属陶瓷的断裂韧性随硬质相粒度的增大而减小,而WC基金属陶瓷的断裂韧性随硬质相粒度的增大而增大。产生上述现象的主要原因与硬质相的晶体结构有关:在室温条件下,面心立方结构的Ti(C,N)晶体中可能存在｛110｝<11 0>和｛111｝<11 0>两个滑移族(含18个独立滑移系);裂纹从一个Ti(C,N)颗粒扩展至另一个Ti(C,N)颗粒时很容易形成取向有利。当Ti(C,N)颗粒较粗时,极易发生穿晶断裂,并且裂纹连续穿晶扩展时亦不会发生显著的偏转或分叉,Ti(C,N)呈现较强的脆性断裂特征。而密排六方结构的WC晶体只有｛101 0｝<112 3>一个滑移族(含4个独立的滑移系);由于取向不利,裂纹难以连续穿晶扩展,且随WC粒度的增大,其对裂纹的偏转和分叉作用增强,从而导致断裂面表面积增大而增韧。     

Microstructure and wear properties of tungsten carbide reinforced steel matrix composites

WC（27%） reinforced steel matrix composites were produced by using an electroslag melting casting technique. The microstructure of the material was characterized using scanning electron microscopy（SEM）, optical microscopy and X-ray diffraction （XRD）. Energy dispersive spectroscopy（EDS） and transmission electron microscopy were performed to investigate the interracial composition between WC particle and steel matrix. The results reveal that the WC particles are partially melted into the steel substrate. At the same time, a reaction layer was detected along with the periphery of WC particle, which significantly enhances the bonding strength of the interface. A slipping wear （high stress abrasion） test was utilized to understand the wear behavior of this material. Abrasive experiment displays a better wear resistance than unreinforced steel matrix when coarse WC particles are dispersed into it. The coarse particles provide greater wear-resistance than the fine particles and operatively takes on the most applied loads. Additionally, the large particles have not been peeled during the wear process for a long time, which indicates the effect of interfacial reaction on wear behavior at the ambient temperature. A double carbide （Fe, W）3C is detected in the interface zone between particles and matrices using transmission electron microscopy.     

On the contiguity of carbide phase in WC–Co hardmetals

In this paper the analysis of dependence of carbide phase contiguity in WC–Co hardmetals on the variation coefficient of WC grain size distribution is carried out. The relationship proposed is

C=1−V_Co^0.644exp(0.391V)

Here C is the contiguity, V_Co is the volume fraction of binder and V is the coefficient of variation. This relation is obtained on the basis of experimental data available in the literature. The basic meaning of this model is that with its help one more microstructural parameter V is introduced explicitly. This parameter essentially affects the mechanical behaviour of WC–Co hardmetals.     

用超急冷降低硬质合金中碳化钨的接触率

论述了硬质合金中的碳化钨接触对硬质合金性能的危害性、碳化钨接触的生成原因和机制，以及用超急冷处理降低碳化钨接触的工艺措施的效果。     

Radically different effects on materials by separated microwave electric and magnetic fields

Using a 2.45 GHz wave-guided cavity, in a single mode TE₁₀₃ excitation, we were able to physically locate compacted 5 mm pellets of samples separately at the H (magnetic) node (where the E field is nearly zero), or the E (electric) node (where H field is nearly zero). A preliminary survey of a variety of metals, (Cu, Fe, Co..) ceramics (ZnO, etc.), and composites, (WC-Co, ZnO-Co) showed remarkable differences in their heating behaviors. The results establish conclusively that the magnetic field interaction contributes greatly to microwave heating of common materials in a manner, previously neglected in most theories of microwave heating, albeit still to be understood. Received: 15 June 2001 / Accepted: 15 June 2001     

激光-感应复合熔覆Ni基WC复合层的工艺研究

为了提高熔覆效率与消除熔覆层的裂纹,采用激光-感应复合熔覆的方法在A3表面获得了无气孔与裂纹的Ni基WC复合层。研究了不同的加工参量对复合层质量的影响,结果表明,随着激光比能的增加,粉末面密度增加;在相同的激光比能条件下,随着粉末面密度增加,熔覆层的高度增加,稀释率减小;在相同的粉末面密度条件下,随着激光比能的增加,熔覆层的宽度略有增加。此外,相对于单纯的激光熔覆技术,激光-感应复合熔覆的效率约可以提高5倍。在激光-感应复合熔覆过程中,熔覆层与基材间的温度梯度大大降低,这是Ni基WC复合层无裂纹的关键原因。