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911.
激光表面合金化制备TiC颗粒增强复合材料微观结构及磨擦学性能研究 总被引:1,自引:0,他引:1
To strengthen the wear resistance of AISI321 stainless steel, the TiC carbide-reinforced composite coating was produced by laser surface alloying. The microstructure, microhardness, and wear resistance of the composite coatings were investigated using optical microscopy, X-ray diffraction (XRD) meter, scanning electron microscopy (SEM), microhardness tester, and sliding wear tester. The results show that the composite coating is metallurgically bonded to the substrate and the microstructure is fine and uniform. The hardness of the composite coating is up to 400 HV, which is 2.5 times that of the substrate. Under room temperature and oil lubrication condition, the sliding wear tests indicate the friction coefficient and weight loss of the composite coating are smaller than those of substrate. The worn surface of the composite coatings is much smoother than that of the substrate, without grooves and crater. The wear resistance of the material has been greatly improved by laser surface alloying. 相似文献
912.
913.
Paul Lauro Sung K. Kang Won Kyoung Choi Da-Yuan Shih 《Journal of Electronic Materials》2003,32(12):1432-1440
The microstructure property relations of several Pb-free solders are investigated to understand the microstructural changes
during thermal and mechanical processes of Pb-free solders. The Pb-free solder alloys investigated include pure Sn, Sn-0.7%
Cu, Sn-3.5% Ag, and Sn-3.8% Ag-0.7% Cu (in weight percent). To reproduce a typical microstructure observed in solder joints,
the cooling rate, ingot size, and reflow conditions of cast alloys were carefully controlled. The cast-alloy pellets are subjected
to compressive deformation up to 50% and annealing at 150°C for 48 h. The microstructure of Pb-free solders is evaluated as
a function of alloy composition, plastic deformation, and annealing. The changes in mechanical property are measured by a
microhardness test. The work hardening in Sn-based alloys is found to increase as the amount of alloying elements and/or deformation
increases. The changes in microhardness upon deformation and annealing are correlated with the microstructural changes, such
as recrystallization or grain growth, in Pb-free solder alloys. 相似文献
914.
S.S. Abd El Rehim Magdy A.M. Ibrahim M.M. Dankeria 《Journal of Applied Electrochemistry》2002,32(9):1019-1027
Cobalt electrodeposited onto steel substrate was carried out from solutions containing cobalt sulfate, boric acid and sodium gluconate. The study dealt with the influence of bath composition, current density, pH and temperature on the potentiodynamic cathodic polarization curves, cathodic current efficiency, and throwing power, as well as the throwing index of these baths. The microhardness of cobalt electrodeposited from gluconate baths is generally high and higher than that of cobalt deposited under similar conditions from sulfate, chloride, bromide and acetate baths. The surface morphology of the as-deposited cobalt was investigated using scanning electron microscopy (SEM) while the structure was studied using X-ray diffraction analysis. Cyclic voltammetric, as well as current-transient, techniques recorded on a glassy carbon electrode suggested that the deposition of cobalt from gluconate bath occurs via a nucleation process under charge transfer control. 相似文献
915.
Oxidation kinetics in either air or oxygen of prenitrided Ti-4.32 wt.% Nb alloy are investigated in the temperature range of 900–1200°C. Based on X-ray and electron microprobe analyses, thermogravimetric measurements, microhardness data, and sintering experiments, a quantitative oxidation model is developed to explain the gas-metal reactions. Temperature cycling experiments, in the temperature range of 900–1200°C and for a 12-hr duration, are performed in an attempt to reduce the oxidation rates of the alloy in air or oxygen. The oxidation resistance of nitrogen pretreated alloy is comparable to that in air and it is considerably higher than in oxygen alone.Presently on academic leave at Max-Planck-Institut für Metallforschung, Institut für Werkstoffwissenschaften, Stuttgart, Bundesrepublik Deutschland. 相似文献
916.
Ni基合金表面激光熔覆Co基合金的组织与性能 总被引:3,自引:0,他引:3
用同步送粉法,在Ni基合金表面上制取了Hoegan aes Co基合金(HMSP 2537)的激光熔覆层。利用金相显微镜,扫描电镜,X射线衍射仪,显微硬度计对熔覆层的组织,相结构,硬度进行了分析和测试。结果显示,熔覆层的不同区域组织及性能不均匀;激光输入功率增大,枝晶间距增大,硬度降低。 相似文献
917.
碳钢Cr-Ti共渗及Al-Ti共渗层的组织和性能 总被引:1,自引:1,他引:1
为了提高碳钢构件的硬度、耐磨性和耐蚀性,对35钢及20钢实施Cr—Ti共渗及Al-Ti共渗,用X射线、EPMA、显微硬度及摩擦磨损实验等分析测试方法,研究了渗层的组织和性能.结果表明,35钢Cr—Ti共渗层外侧富Cr、内侧富Ti,在3.5%NaCl和10%H2SO4溶液中有良好的耐蚀性;渗层表面硬度HV0.2=1900,耐磨性比17Cr2Ni2Mo渗碳钢对比试样提高3倍.35钢Al—Ti共渗层外侧富Ti、内侧富Al,在10%H2SO4溶液中的耐蚀性较差;渗层表面硬度为HV0.2=400,但耐磨性仍比对比试样提高近一倍。 相似文献
918.
919.
Biktor F. Gorban’ V. B. Vinokurov O. N. Grigor’ev Alexander N. Demidik Inna I. Ivanova A. Yu. Koval’ V. A. Kotenko Engel’s P. Pechkovskii Sergei A. Firstov 《Powder Metallurgy and Metal Ceramics》2005,44(3-4):181-190
We have studied the behavior of titanium silicon carbide Ti3SiC2 in different structural states (one-phase and two-phase, compacted, porous) during microindentation (load up to P = 0.9 N) at room temperature with automatic recording of the loading, holding, and unloading diagrams. We used scanning electron microscopy to study the microstructure around the macrohardness indentations (P = 10–200 N). The results obtained are compared with corresponding data for a number of metallic and ceramic materials. On the P - h loading diagrams (h is the penetration depth), we observe plateaus which are the result of microfracture of the material under the indentor. This reflects the characteristics of titanium silicon carbide: when it is loaded, intergrain and intragrain microcleavage occurs. The plasticity (or pseudoplasticity) of the material can be characterized using the relative work dissipated in the deformation, i.e., expended for irreversible deformation, which can be determined during microindentation: λ p = A
p
/A.__________Translated from Poroshkovaya Metallurgiya, Nos. 3–4(442), pp. 93–105, March–April, 2005. 相似文献
920.