WC－Co硬质合金中η相的X射线定量测定

根据烧结过程中Ｗ元素的质量守恒，推导出ＷＣ—Ｃ硬质合金中ＷＣ相和η１相（Ｗ３ＣＯ３Ｃ）含量间的关系式，进而导出ＷＣ相和η１相间的相对Ｋη１ＷＣ值表达式，从而建立了一种用Ｘ射线衍射方法定量测定ＷＣ—Ｃｏ合金中η１相含量的实用方法。     

QUANTITATIVE X-RAY DETERMINATION OF η-PHASE IN WC-Co CEMENTED CARBIDES

根据烧结过程中Ｗ元素的质量守恒，推导出ＷＣ－Ｃｏ硬质合金中ＷＣ相和η相（Ｗ３Ｃｏ３Ｃ）含量间的关系式，进而导出了ＷＣ相和ηｌ相间的相对Ｋ值表达式，从而建立了一种用Ｘ射线衍射方法宣测定ＷＣ－Ｃｏ合金中η相含量的实用方法。     

计算机支持的协同工作概观

ＣＳＣＷ是一门多学科交叉的新兴课题。本文介绍ＣＳＣＷ起源和发展,讨论了ＣＳＣＷ３的主要研究内容,核心课题和应用领域。     

电镀

20 0 2 0 70 1　ＺｎＣｌ2 ＮａＣｌ(摩尔分数 4 0 %～ 6 0 % )熔盐电沉积Ｗ———ＭａｓｕｄａＭ .ＪＥｌｅｃｔｒｏｃｈｅｍＳｏｃ,2 0 0 1,14 8(1) :5 9(英文 )用伏安法研究了含不同Ｗ化合物的ＺｎＣｌ2 ＮａＣｌ(摩尔分数4 0 %～ 6 0 % )熔盐在 4 5 0℃下Ｗ的电沉积 ,在恒定电位下 ,使用含ＷＯ3、Ｋ2 ＷＯ4 、ＷＣｌ4 、Ｋ2 ＷＣｌ6 的镀槽可以获得金属Ｗ ,但含Ｋ3Ｗ2 Ｃｌ9和ＷＣｌ2 的镀槽不能获得金属Ｗ层。2 0 0 2 0 70 2　Ｓｎ Ｚｎ合金电镀———ＲａｓｍｕｓｓｅｎＪ .Ｐｌａｔｉｎｇ＆ＳｕｒｆａｃｅＦｉｎ ,2 0 0 1,88(2 ) :…     

爆炸喷射沉积WC-Co涂层组织及显微硬度分析

分析测试了通过爆炸喷射沉积获得的ＷＣ－Ｃｏ／Ｍ基复合材料的微观组织结构及显微硬度。试验结果表明，爆炸喷射沉积层组织形态为粗大、彼此重叠的片层状；主要组成相为ＷＣ、Ｗ、Ｃｏ及少量的Ｗ２Ｃｏ经８００℃／２ｈ热处理之后，出现了原子迁移，组织进一步均匀，并形成了新相Ｃｏ３Ｗ３Ｃ。涂层的显微硬度随处理温度升高和Ｃｏ含量增加而降低，且具有明显的各向异性。     

（WC—Co／NiCrBSi）钎焊涂层结合机制及磨损性能研究

采用真空钎焊工艺,将ＷＣ－Ｃｏ硬质合金粉和ＮｉＣｒＢＳｉ（ＡＷＳＢＮｉ－２）合金粉钎焊到４５＃钢表面,得到（ＷＣ－Ｃｏ／ＮｉＣｒＢＳｉ）钎焊涂层。     

纳米WC硬质合金的制备、结构和力学性能

本文综述了纳米ＷＣ硬质合金的制备、结构和力学性能的研究现状，并将其与传统的ＷＣ硬质合金进行了比较，表明纳米ＷＣ硬质合金具有更优异的物理性能。另外，结合自己的研究工作，阐述了化学机械合金化法制备纳米Ｗ２Ｃ粉体的动力学特点。     

纳米WC硬质合金的制备,结构和力学性能

本文综述了纳米ＷＣ硬质合金的制备，结构和力学性能的研究现状，并将其与传统的ＷＣ硬质合金进行了比较，表明纳米ＷＣ硬质合金具有更优异的物理性能。     

(WC-Co/NiCrBSi)钎焊涂层结合机制及磨损性能研究

采用真空钎焊工艺,将ＷＣ－Ｃｏ硬质合金粉和ＮｉＣｒＢＳｉ（ＡＷＳＢＮｉ－２）合金粉钎焊到４５＃钢表面,得到（ＷＣ－Ｃｏ／ＮｉＣｒＢＳｉ）钎焊涂层。不同钎焊工艺下,涂层及涂层／基体的拉伸强度分别达１００—１４０ＭＰａ和３００－３６０ＭＰａ。初步分析了钎焊涂层结合机制。涂层的磨料磨损性能远高于同配比的火焰堆焊涂层及Ｃｏ－Ｃｒ－Ｗ堆焊层     

（Ni—W）—WC复合镀层的研究

研究了Ｎｉ－Ｗ合金镀液中添加ＷＣ微粒制备（Ｎｉ－Ｗ）－ＷＣ复合镀层的电沉积过程，表征镀层的结构２和形貌，测试镀层在碱性溶液中的电催化氢析氧性能，探讨镀层的耐蚀性结果表明：（Ｎｉ－Ｗ）－ＷＣ为晶态复合镀层，析氢析氧性能优越，耐蚀性优良。     

Detailed investigation of the temperature dependence of ionic transport parameters of a new composite electrolyte system (1−x) (0.75AgI : 0.25AgCl) : xSnO2

Detailed investigations of a new Ag+-ion-conducting two-phase composite electrolyte system (1–x) (0.75AgI : 0.25AgCl) : xSnO2 are reported, where 0x50 in weight per cent. A quenched-and-annealed (0.75AgI : 0.25AgCl) mixed system–solid solution was used as the first phase instead of the commonly used host matrix salt AgI. Micron-sized particles (about 10 m) of SnO2 were dispersed in the first (matrix) phase. The composition 0.8(0.75AgI : 0.25AgCl) : 0.2SnO2 exhibited conductivity enhancements of more than eight times over the annealed host and about three times over the quenched host at room temperature and has been referred to as optimum composition. The existence of two separate phases has been ascertained by X-ray diffraction and differential thermal thermal analysis techniques. The temperature dependence of the electrical conductivity, , ionic mobility, , mobile ion concentration, n, ionic transference number, tion, and ionic drift velocity, vd, are also reported. The enhancement in the conductivity in this two-phase composite electrolyte has been attributed to the increase in ionic mobility at room temperature.     

Laser surface coating of Mo–WC metal matrix composite on Ti6Al4V alloy

Laser surface alloying of Mo, WC and Mo–WC powders on the surface of Ti6Al4V alloys using a 2 kW Nd-YAG laser was performed. The dilution effect upon the microstructure, microhardness and wear resistance of the surface metal matrix composite (MMC) coating was investigated. With a constant thickness of pre-placed powder, the dilution levels of the alloyed layers were found to increase with the incident laser power. The fabricated surface MMC layer was metallurgically bonded to the Ti6Al4V substrate. The microhardness of the fabricated surface layer was found to be inversely proportional to the dilution level. The EDAX and XRD spectra results show that new intermetallic compounds and alloy phases were formed in the MMC layer. With the existence of Mo content in the pre-placed powder, the β-phase of Ti in the MMC coating can be retained at the quenching process. With increasing weight percentage content of WC particles in the Mo–WC pre-pasted powder, the microhardness and sliding wear resistance of the laser surface coating were increased by 87% and 150 times, respectively, as compared with the Ti6Al4V alloy. The surface friction of the laser-fabricated MMC coatings was also decreased as compared with the worn Ti6Al4V substrate.     

Effect of bonding time on joint properties of vacuum brazed WC – Co hard metal/carbon steel using stacked Cu and Ni alloy as insert metal

Abstract

Hard metal WC – Co and carbon steel were successfully joined using double layered Cu alloy and amorphous Ni alloy as inert metal and an oil cooling method after brazing. Defects such as cracks and voids were not formed near the bonded zone. This result means that double layered insert metals and oil cooling minimised the residual stress near the bonded zone after brazing. The shear strength of the joints decreased with increasing bond time. The reasons why the shear strength decreased as bond time increased could be many, including shape of the interface, formation and growth of brittle intermetallic compounds, and coarsening of WC particles near the bond zone. The maximum shear strength of the joints was 310 MPa under conditions 0·6 ks bond time and 8 wt-%Co content in the WC hard alloy.     

激光增材制造镍基复合材料界面连接机制与断裂行为

基于颗粒增强镍基复合材料优异的结构/功能特性，在航空航天、核电军工和电子电工等领域有着广泛的应用前景。本文选用机械球磨混粉+激光选区熔化方法 (SLM)制备了碳化钨(WC)颗粒增强IN718复合材料(WC/IN718)，对复合材料内部异质界面连接机制、强化机制和断裂行为进行了分析。研究结果表明：随着WC颗粒含量的增加(0wt%～20wt%)，试件成形良好，WC颗粒均匀分布在基体内部，异质界面处无缺陷产生，界面处产生了贫碳的W₂C层和碳化物层，基体合金主要呈柱状晶生长。由于熔池内部能量密度分布不同，低温位置WC颗粒的断裂方式为先形成界面反应层后由热应力引起断裂，高温位置WC颗粒优先发生断裂，断裂成小尺寸颗粒，后与熔化的基体合金形成界面反应层，弥散分布在基体内部。随着WC颗粒含量的增加，复合材料的强度呈现升高的趋势，而断裂韧性降低，抗拉强度最高可达1 280 MPa，强化机制主要为载荷传递强化，断裂机制为WC颗粒的脆性断裂和基体合金的韧性断裂。     

Ionic transport in the (Agl∶AgCl) mixed-system

Ionic mobility, conductivity, number of charge carriers and transference number are reported for annealed and rapidly quenched [xAgl(1–x)AgCl] mixed systems, these results are compared with Agl. Of these three materials the quenched mixed-system had the highest Ag⁺ ion conductivity. Further, preliminary studies are reported where the high conductivity system (i.e. quenched 0.75 Agl0.25 AgCl) has been used as host material for the preparation of Ag⁺ ion conducting glasses and composites. Detailed thermal/phase diagram studies have also been carried out on the quenched composition. The conductivity enhancement in the quenched system is attributed to the formation of new disordered phases and the introduction of amorphisity, the simple space-charge model applicable to the annealed system failed to explain these results.     

The sinterability of ultrafine WC powders obtained by a CVD method

The sintering behaviour of ultrafine WC powders produced by a CVD method (particle size <0.3m) and commercial WC powders (particle size ~ 1m) is investigated in hydrogen and in vacuum. It has been found that ultrafine WC powders have an extremely high sinterability and give a sintered body with a relative density of 100% by sintering at a considerably lower temperature than normal, such as 1750° C. Also WC powders with a large particle size and a wide-size distribution have a high sinterability caused by the presence of fine particles and the sinterability of WC powders is influenced significantly by the sintering atmosphere. The atmospheric effect is discussed in connection with the heating behaviour of a surface oxide layer and free carbon.     

Vacancy enhancement of μ-phase precipitation in Ag-10 at % Al alloy

Locally prepared and homogenized Ag-10 at% Al wires were quenched from 400° C to room temperature followed by different ageing treatments at temperatures in the precipitation zone to obtain samples with different amounts of-phase precipitation. Room temperature steady state creep and microhardness tests were performed in order to assess the degree of precipitation in the samples. Increased precipitation of thephase was found to decrease the strain rate and to increase the hardness. The precipitation process was possibly enhanced by the quenched vacancies. X-ray analysis after creep fracture revealed a remarkable drop in the integral intensities, indicating the destruction of the ordered structure of the-phase, i.e. partial redissolution of it.     

钢表面颗粒增强熔覆层的组织和性能

采用预置法在45号钢表面制备WC颗粒增强熔覆层,研究了熔覆层的组织和性能,并与淬火态Cr12MoV(59HRC)的耐磨性能进行比较,分析磨损机理并讨论WC颗粒的磨损现象。结果表明:熔覆层与基材之间结合良好并形成界面反应层;熔覆层组织分布均匀,表面弥散分布着大量WC颗粒;熔覆层的平均硬度比基材的高,耐磨性是基材45号钢的18倍,是淬火态Cr12MoV的2倍;在磨损实验中熔覆层的增强颗粒WC出现罕见的表面磨平和脆性脱落现象。     

The effect of direct electric current on precipitation in a bulk Al-4 wt % Cu alloy

The effect of the stress of direct electric current on precipitation in a quenched Al-4.15 wt % Cu alloy is investigated by measurement of the change in electrical resistance of a bulk specimen as a function of current density up to about 3000 A cm^–2 at a given annealing time. A similar effect of d.c. stress is observed at 50, 75 and 100 C. For a lower current density, a constant or slightly increasing resistance is observed, while for a current density higher than a critical value, the resistance decreases with an increase in density. On the assumption that the temperature increase of a specimen due to the Joule heating is proportional to the square of the current density, it is concluded that there exists some effect of d.c. stress per se to prevent the precipitation reaction, aside from the effect of the temperature increase due to the Joule heating, and it is suggested that this retarding effect is related to the sweeping out of quenched-in excess vacancies into grain boundaries by electromigration.