Z. X. Lee
,
F. P. Huang and W. Y. Zhang Tianjin University
,
Tianjin 300072
,
China
金属学报(英文版)
Using Fourier's conduction equation, a mathematical model of the temperature field for the coat of coat-cast technology is established. The relationship between the thickness, quality of the coat and casting temperature of liquid iron is analyzed. The results show that the coat quality is reliable; the combination of the coat with the base is solid; because foe temperature gradient of the coat is not large, the surface, middle and bond area of the coat are melted completely and the thickness of the coat can reach 2.3mm by using self-melting spraying alloy powder when the casting temperature is higher than 1380℃. In addition, the agreement between the calculated and measured values is good. This paper is of significant meaning for coat-cast technology and the coat quality.
关键词:
coat-cast
,
null
,
null
,
null
Journal of Materials Research
The morphology of the dark and bright regions observed by transmission electron microscopy for the Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass strongly depends on the ion beam parameters used for ion milling. This indicates that the ion beam could introduce surface fluctuation to metallic glasses during ion milling.
关键词:
room-temperature
马保国
,
许婵娟
,
钟开红
,
蹇守卫
,
李相国
材料科学与工程学报
doi:10.3969/j.issn.1673-2812.2005.04.006
本文系统地研究了F、S、P元素对水泥熟料矿物形成过程和组成的影响及其叠加矿化效应,并通过化学分析和XRD分析探讨了其作用机理.研究结果表明:F、S、P元素在水泥烧成中均可降低液相出现和C3S形成温度,改善易烧性,但F、S叠加矿化效果最好,而且可以改善熟料的矿物组成及性能,避免了单掺F造成的熟料活性降低等问题.
关键词:
矿化效应
,
氟石膏
,
磷石膏
,
易烧性
Z.C. Guo
,
X.Y. Zhu
金属学报(英文版)
The effects of pulse frequency f and duty cycle r on the deposition rate, composition, morphology, and hardness of pulse electrodeposited RE (rare earth)-Ni-W-P-SiC composite coatings have been studied. The results indicate that pulse current can improve the deposition rate of RE-Ni-W-P-SiC composite coatings; W, P, and SiC contents in the coating decrease with the increase of pulse frequency and reach the lowest value at f = 33Hz, whereas the RE content in the composite coatings increases with increasing
pulse frequency. SiC content decreases with the increase of duty cycle, W content reaches the lowest value, and P content reaches the highest value at r = 0.4; pulse current and RE can lead to smaller size of the crystalline grains; however, the effects of different pulse frequency and duty cycle on the morphologies of RE-Ni-W-P-SiC composite coatings are not obvious. The hardness of
RE-Ni-W-P-SiC composite coatings is the highest when the duty cycle is at 0.6 and 0.8 and pulse frequency is at 50Hz. At the same pulse frequency, the hardness of RE-Ni-W-P-SiC composite coatings at r = 0.8 is higher than that at r = 0.6.
关键词:
pulse frequency
,
null
,
null
Materials Characterization
This paper describes work performed to determine some of the properties of the electroless Ni-W-P amorphous deposits. Phosphorus contents were varied up to 32 at.%, and the amorphous structure was found to be present at phosphorus contents above 5 at.%. Irrespective of P content, all the deposits exhibited excellent adhesion to metallic substrates. The addition of even small amounts of W provided greatly increased hardness compared with the plain Ni-P deposits. The wettability properties of the Ni-W-P deposits were found to be comparable to those of Ni-P and N-B-P deposits but inferior to those of Ni-B deposits. (C) Elsevier Science Inc., 1996
关键词:
nickel
黄远辉
,
杨海涛
,
尚福亮
,
吴国根
,
汪晓
稀有金属材料与工程
用高温固相反应法制备出A_2W_3O_(12) 型稀土钨酸盐材料(A=Y,Er,Ho,Yb),用室温及高温XRD测定其在不同温度下的结构、晶胞参数及晶胞体积,并用TOPSA软件对其结构进行精修.发现除HO_2W_3O_(12)外,都具有较大的负热膨胀系数.据A. W. Sleight预测,HO_2W_3O_(12)具有较大的负热膨胀特性,但本实验却发现它并没有负热膨胀性,反而具有非常大的正热膨胀系数.
关键词:
稀土钨酸盐
,
高温XRD
,
HO_2W_3O_(12)
熊进辉
,
黄继华
,
薛行雁
,
张华
,
赵兴科
,
林国标
航空材料学报
doi:10.3969/j.issn.1005-5053.2009.6.010
本文利用AgCuTi-W复合钎料作中间层,在适当的工艺参数下真空钎焊C_f/SiC复合材料与Ti合金,利用SEM,EDS,XRD分析接头微观组织结构,利用剪切试验检测接头力学性能.研究结果表明:钎焊时,复合钎料中的Ti借助Cu-Ti液相与C_f/SiC复合材料反应,在C_f/SiC复合材料与连接层界面形成Ti3SiC2,Ti3Si和少量TiC化合物的混合反应层.复合钎料中的Cu与Ti合金中的Ti发生互扩散,在连接层与Ti合金界面形成不同成分的Cu-Ti化合物过渡层.钎焊后,形成W颗粒强化的致密复合连接层,W颗粒主要分布在Cu-Ti相中.W的加入缓解了接头的残余热应力,C_f/SiC/AgCuTi-W/TC4接头剪切强度明显高于C_f/SiC/AgCuTi/TC4接头.
关键词:
C_f/SiC
,
Ti合金
,
钎焊
,
AgCuTi-W
胡光辉
,
杨防祖
,
王森林
,
吴辉煌
材料保护
doi:10.3969/j.issn.1001-1560.2003.06.005
测量了化学镀Ni-P和Ni-W-P过程混合电位随时间的变化,并分析其变化规律.指出Emix的正移与pH值随时间而降低有关,而且pH值的降低会加速化学镀的诱发过程.低碳钢诱发化学镀Ni-W-P会在混合电位-时间曲线上出现两个电位阶梯,其原因在于低碳钢在给定的镀液体系中稳定电位不够负,不能提供足够的能量使化学镀Ni-W-P快速发生,只有当表面形成达到一定覆盖度的具有催化活性的Ni原子层后,才能迅速地诱发化学镀过程;而Ni-P和Ni-W-P的稳定电位足够负,可以使化学镀过程快速诱发,故仅有一个电位阶梯.
关键词:
化学镀
,
Ni-P
,
Ni-W-P
,
混合电位
郑明新
,
朱永华
,
张翔
材料研究学报
本文中提出了一种可获得非晶态镀层的Co-W-P 合金电刷镀液。试验表明,Co-W-P 镀层从大约350℃起发生晶化,并同时发生Co_2P 的沉淀析出过程,产生二次硬化效应,而使红硬性提高。将这种镀层应用于热模具,可提高模具使用寿命50—200%;应用于冷模具时,也能使寿命大幅度提高。所以,非晶态Co-W-P 合金镀层的刷镀技术,是一种可提高模具寿命的新的表面强化处理方法。
关键词:
