WC—Co硬质合金的元素组成及化学状态的XPS分析

试样为未脱蜡ＷＣ－１０Ｃｏ硬质合金，在Ｎ２气氛下采用微波快速烧结。用ＸＰＳ灵敏度因子法分析了生坯、正常烧结样品及过烧样品的Ｗ、Ｃ、Ｃｏ化学状态及其相对含量异同。测得样品中Ｗ、Ｃ原子比同理论比基本一致，Ｃｏ的重量百分数同实际配比基本接近，从ＸＰＳ全区扫描谱线中的Ｎ１Ｓ峰观测说明，在Ｎ２气氛保护下样品不氮化。本文还着重就ＷＣ－Ｃｏ硬质合金碳的化学状态进行定量测定，结果表明，未脱蜡烧结后的样品中出现大量     

非均匀结构WC—Co硬质合金

对采用碳化烧结法制取非均匀结构硬质合金的工艺进行了研究。结果表明，碳化烧结工艺可制得非均匀结构ＷＣ－Ｃｏ硬质合金，配Ｃ量以６．０％￣６．１％（质量分数）较好，最佳烧结温度为１４２０￣１４５０℃。ＷＣ－１０％Ｃｏ（质量分数）合金的抗弯强度бｂｂ可达２６００￣２９００ＭＰａ，密度ｐ为１４．４￣１４．６ｇ／ｃｍ＾３，硬度ＨＲＡ为８８．２￣８９．９。此外，还可以获得ＷＣ〈１μｍ的合金。     

热—力循环对热处理硬质合金钴相结构的影响

用Ｇｌｅｅｂｌｅ－１５００动态应力应变／热模拟试验机对ＷＣ－２０％Ｃｏ（质量分数）热处理硬质合金进行热－力循环实验，借助ＸＲＤ技术分析计算了合金中钴粘结相的相组成，并在ＳＥＭ下观察了合金的微观组织。结果表明：合金烃热－力循环后，钴相中面心β－Ｃｏ含量降低，密排六方α－Ｃｏ含量相应升高；热处理合金钴相中面心钴相对体积百分含量下降的程度低于常规烧结合金。热处理硬质合金制品使用寿命的提高与合金中钴相相结     

WC-Co梯度硬质合金的渗碳处理工艺

对表面贫钴的无η相WC-Co硬质合金进行渗碳热处理制备梯度硬质合金。通过正交试验探究了各工艺参数对梯度结构的影响;利用极差分析与方差分析法确定最佳渗碳工艺参数水平。结果表明:各工艺参数对梯度结构和贫Co幅度的影响程度依次是渗碳温度、甲烷体积分数、渗碳时间及混合气体流速。随渗碳温度的升高和渗碳时间的延长,梯度层厚度和贫Co幅度增大;随甲烷体积分数的增大,梯度层厚度和贫Co幅度减小;随混合气体流量的增加,梯度层厚度和贫Co幅度先增大、后减小;最终确定了合理的制备工艺参数,即渗碳时间t=120min,渗碳温度T=1 420℃,甲烷体积分数φ=1.5%,混合气体流量qV=8L·min-1。     

关于镁白云石质耐火材料高温相组成计算的改进

对原始CaO-MgO-C2S-C4AF系统锥形投影相图按正三角形进行了重新绘制，并提高了模数坐标线密度，使得利用该相图计算镁白云石质耐火材料高温相组成的精确度得到显著提高。     

超细晶粒WC硬质合金的研制动态

论述了超细晶粒WC硬质合金经历的从普通合金、亚微细晶粒合金到超细乃至纳米晶粒合金三大发展阶段,它们在金属加工、电子工业、木材加工、医学等领域的主要应用,以及有关的粉末原料和合金的最新研制动态     

CoWO4-WO3纳米复合粉体的合成及其研究

采用共沉淀法制得了超细粒碳化钨钴金属陶瓷前驱体原料CoWO4－WO3纳米复合粉体,其粒径约10nm,结构特征为非晶态。探讨了合成条件对产物性能的影响,并采用TG-DTA,XRD,TEM等测试方法对粉体的特性以及反应机理进行了研究。     

WC－Co硬质合金的元素组成及化学状态的XPS分析

试样为未脱蜡ＷＣ－１０Ｃｏ硬质合金，在Ｎ２气氛下采用微波快速烧结．用ＸＰＳ灵敏度因子法分析了生坯、正常烧结样品及过烧样品的Ｗ、Ｃ、Ｃｏ化学状态及其相对含量异同．测得样品中Ｗ、Ｃ原子比同理论比基本一致，Ｃｏ的重量百分数同实际配比基本接近，从ＸＰＳ全区扫描谱线中的Ｎ１Ｓ峰观测说明，在Ｎ２气氛保护下样品不氮化．本文还着重就ＷＣ－Ｃｏ硬质合金碳的化学状态进行定量测定，结果表明，未脱蜡烧结后的样品中出现大量石墨相．     

Microstructure and properties of gradient cemented carbide with Nano-TiN

Gradient cemented carbides with nano-TiN were prepared by the common powder metallurgical procedure. The formation of gradient zone and the microstructure, properties of the alloys were investigated using scanning electron microscope（SEM）, energy dispersive spectroscopy（EDS） and other performance testing apparatus. Moreover, the effect of nano-TiN on the gradient cemented carbide was studied. It is found that gradient zone width increases slightly with nano-TiN introduction. Both cobalt and titanium concentrations reach the maximum near the gradient border. Tungsten concentration shows fluctuation from the surface to the bulk. （Ti ,W）C phase grains are refined for nitrogen introduction. Core-rim structure has been observed under the SEM back-scattered mode. The core appears as dark due to more titanium in it and the rim with more tungsten appears as grey. In addition, the hardness and transverse rupture strength of gradient cemented carbide are enhanced with nano-TiN introduced.     

Phase composition, transition and structure stability of functionally graded cemented carbide with dual phase structure

The phase composition, phase transition and phase structure transformation of the wire-cut section of functionally graded WC-Co cemented carbide with dual phase structure were investigated by XRD phase analysis. It is shown that the composition of η phase in the core zone is Co3W3C （M6C type）. The structure of cobalt based solid solution binder phase is fcc type. At the cooling stage of the sintering process, the phase transition of η phase, i.e. M6C→M12C and the martensitic phase transition of the cobalt based solid solution binder phase, i.e. fcc→hcp are suppressed, which facilitates the strengthening of the alloy. Because the instantaneous temperature of the discharge channel is as high as 10 000 ℃ during the wire cutting process, the processed surface is oxidized. Nevertheless, the oxide layer thickness is in micro grade. In the oxide film, η phase is decomposed into W2C and CoO, and cobalt based solid solution binder is selectively oxidized, while WC remains stable due to the existence of carbon containing liquid organic cutting medium.     

Phase transformation of nano-grained W(Co, C) composite powder and its phase constitute

1 INTRODUCTION Nano-grained WC-Co cemented carbides with high toughness and high hardness have drawn extensive attention of hard metal industry[1?2]. There are two key processes for the fabrication of this high performance alloy[3?4]. One is the preparation of nanometer WC-Co composite powders, the other is the effective control of grain growth during sintering. At present, great technical breakthrough has been achieved in the preparation of nanometer powders. The typical methods of na…     

硬质合金中温钎焊技术的实验研究

采用显微结构法,通过观察钎焊接头形成条件,研究了以B-Ag-1为钎料的硬质合金和钢的中温连接技术。实验表明,在感应电流为450～600 A时,B-Ag-1钎料能湿润并在硬质合金上铺展,形成组织均匀的钎缝,同时通过钎料中银原子和铜原子向硬质合金的扩散形成具有一定强度的界面。钎焊温度的降低以及铜缓冲层的加入,大大降低了钎焊过程的热应力,接头和母材上均未发现热裂纹。     

硬质合金中温钎焊技术的实验研究

采用显微结构法,通过观察钎焊接头形成条件,研究了以B-Ag-1为钎料的硬质合金和钢的中温连接技术。实验表明,在感应电流为450～600 A时,B-Ag-1钎料能湿润并在硬质合金上铺展,形成组织均匀的钎缝,同时通过钎料中银原子和铜原子向硬质合金的扩散形成具有一定强度的界面。钎焊温度的降低以及铜缓冲层的加入,大大降低了钎焊过程的热应力,接头和母材上均未发现热裂纹。     

Directional migration behavior of cerium during sintering process of mischmetal doped cemented carbide

Three observation methods were used to investigate the existing form and the behavior of rare earth during the sintering process of high activity mischmetal （RE, with lanthanum and cerium） doped WC-8%Co-0.048%RE（mass fraction） alloy with low carbon-containing level by scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDXS）, considering the fact that the addition amount of rare earth in the alloy is very minute. The directional migration process and mechanism of cerium were discussed. First, the sinter skin （surface） is observed. oxide on the sinter skin, and lanthanum in these cerium observed, and lanthanum containing phase/micro-zone in It is shown that there exists a dispersedly distributed cerium containing enrichment positions is very minute. Secondly, the polished section is the alloy is identified. Finally, based on the fact that the fracture of cemented carbide is resulted from the heterogeneous phase or other defects within the microstructure, the fracture surface is observed and cerium containing phase/micro-zone in the fracture source approximately 260 μm from the surface is identified. These combined observations reveal adequately the fact that lanthanum and cerium get separated and cerium predominantly migrates towards the surface during the sintering process.     

Microstructures and properties of WC-20Co-1Y_2O_3 cemented carbide by hot-press and liquid phase sintering

1　INTRODUCTIONInRef .[1],averyinterestingandinexplicablefindingwasreportedthataspecialwhisker likeWCgrainstructure ,mostintherangeof 10 0 2 0 0nmindiameterand 1 2mminlength ,wasformedinWC 2 0Co 1Y2 O3cementedcarbidepreparedbyhot pressbelowtheeutectictemperature .ItwasmentionedinthepaperthatWCpowderwithFisherSubsiereSizer(FSSS)of 1μm ,ultrafineCopowder ,andY2 O3powderof 1μmwereusedastherawmaterialsofWC 8Cocementedcarbide .However ,whetherthesamerawmaterialswereusedinWC 2 0Co …     

Brazing behavior of ultrafine cemented carbide with stainless steel

In order to investigate the effects of brazing temperature, heating rate and cooling methods on shear strength, hardness, magnetic saturation and coercivity of the ultrafine cemented carbide, the ultrafine cemented carbide was fabricated according to conventional powder metallurgical procedures, and then brazed to the stainless steel with silver-based filler alloy by supersonic frequency induction brazing. The microstructure was observed using scanning electron microscope （SEM）, energy dispersive spectroscopy （EDS） and the magnetic properties were tested utilizing coercimeter and cobalt magnetism instrument. The results show that no micro-crack is found in the cemented carbide after brazing because of silver-based sandwich compound used as filler alloy. In the melted silver layer, there is more carbon in the region adjacent to the cemented carbide. Varied shear strengths, hardnesses, magnetic saturations and coercivities are present under different brazing temperatures, heating rates and coolings. This phenomenon is correlated with some factors such as wettability and fluidity of filler alloy, brazing stress, oxidation of cemented carbide, and allotrope transition of cobalt. Shear strength reaches the maximum of 340 MPa and hardness of ultrafine cemented carbide remains 1879 HV at the brazing temperature of 730℃. The carbon increases with the of increase of the heating rate. What＇s more, and there is no r/phase found under this condition. content decreases with the increase of brazing temperature, and it the lowest magnetic saturation reaches 81.8% of the theoretic value,     

Rare earth doped new cemented carbide with Ni-Co binder for mining

ＴｈｅｗｅａｒｒｅｓｉｓｔａｎｃｅｏｆｔｈｅｔｒａｄｉｔｉｏｎａｌＷＣ Ｃｏｃｅ ｍｅｎｔｅｄｃａｒｂｉｄｅｆｏｒｍｉｎｉｎｇ ,ｗｉｔｈｔｈｅａｄｄｉｔｉｏｎｏｆｒａｒｅｅａｒｔｈ ,ｃａｎｂｅｉｍｐｒｏｖｅｄｏｂｖｉｏｕｓｌｙ[1] .Ｂａｓｅｄｏｎｔｈｅｉｎ ｈｅｒｅｎｔｓｉｍｉｌａｒｉｔｙｂｅｔｗｅｅｎＷＣ ＣｏａｎｄＷＣ Ｃｏ Ｎｉｃｅｍｅｎ ｔｅｄｃａｒｂｉｄｅｓｉｎｔｅｒｍｓｏｆｍｉｃｒｏｓｔｒｕｃｔｕｒｅ ,ｗｅｃａｒｒｉｅｄｏｕｔｔｈｅｓｔｕｄｙｏｆＷＣ Ｃｏ Ｎｉｃｅｍｅｎｔｅｄｃａｒｂｉｄｅｗ…     

WC-Co涂层磨削过程中的温度与相变

针对WC-Co涂层在磨削中磨削温度会引起相变,进而导致磨削缺陷的问题,以DMU70V数控铣床为平台进行WC-Co涂层磨削实验,利用K型热电偶和DGF40N光纤式红外测温仪测量磨削温度,借助x-射线衍射仪分析磨削前后WC-Co涂层物相组成.实验结果表明,利用热电偶测得的磨削温度与根据磨削过程中WC-Co涂层物质相变推测得到的磨削温度相差较大,利用WC-Co涂层物质相变推测的磨削最高温度与DGF40N光纤式红外测温仪测得的磨削最高温度一致,说明可以利用WC-Co涂层物质相变来推测磨削最高温度,为一些不能直接测量磨削温度的场合提供了新方法.WC晶粒在WC-Co涂层干磨削时大多异质生核,磨削后产生的WC晶粒粒度大,从而导致WC-Co涂层的强度下降,WC-Co涂层不宜干磨削.