共查询到16条相似文献,搜索用时 500 毫秒
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研究了合成金刚石用触媒合金的气体渗氮。结果表明,该合金经气体渗氮后,表面形成渗氮层,经X射线分析,渗层由含N的r固溶体和r'-M4N组成。用该合金作为触媒合成金刚石可提高其强度,并随渗氮层厚度的增加强度也增加。 相似文献
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利用组合的二次回归正交实验设计方案 ,对钽低温离子渗氮条件下 ,表面物相及固溶体中氮的含量随渗氮温度、气氛总压力和氢氮摩尔比的变化进行了系统研究。发现表面渗氮层由化合物Ta6N2 .57、超晶格TaN0 .1和固溶体相组成。氮在钽中的固溶度随气压、温度和氢摩尔分数的增加而增加 ,化合物和超晶格相含量随温度增加而增加 ,同时化合物相随氢摩尔分数增加有一个极大值 ,该极大值随温度增加而下降。 相似文献
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利用脉冲直流辉光等离子技术,对1Cr11Ni2W2MoV马氏体热强不锈钢进行不同工艺参数的离子渗氮。利用光学显微镜、显微硬度计、XRD对渗氮层的显微组织及硬度进行了分析。结果表明,在所选用的离子渗氮工艺参数下,1Cr11Ni2W2MoV钢渗层只由扩散层组成,渗氮温度≤560℃时,渗层主要由固溶N原子的α相组成,并伴有少量的γ'-Fe4N和CrN析出;随着渗氮温度的升高和渗氮时间的延长,固溶N原子的α相逐渐转变成γ'-Fe4N相,当处理温度达到590℃时,渗层主要由γ'-Fe4N和Cr N组成。离子渗氮后渗层的表面硬度较未渗氮前有显著的提高,在一定范围内,渗层的表面硬度和渗层深度都随着渗氮温度和渗氮时间的增加而增加,渗层硬度梯度分布也随着渗氮时间的延长变得平缓。 相似文献
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用SEM, XPS对钽及表面离子渗氮层在充分搅拌的50℃的6.5%NaOH中腐蚀前后的表面进行了观察和分析. 证明表面腐蚀产物为NaTaO3和Ta2O5. 结合计算的腐蚀反应的电荷转移数, 给出了钽在碱液中可能的腐蚀反应方程式. 相似文献
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ZHANG Deyuan LIN Qin ZHAO Haomin FEI Qinyong GENG Man National R & D Center for Surface Engineering of China Shenzhen China University of Science Technology Beijing Beijing China 《稀有金属(英文版)》2004,23(2):185-188
The combined quadratic orthogonal regression method of experiment design was employed to explore the effectsof process parameters of plasma nitriding of tantalum such as total pressure, temperature and original hydrogen molar frac-tion on the hardness, roughness and structure of nitriding surfaces. The regression equations of hardness, roughness andstructure were given according to the results of regression and statistic analysis. And the diffusion activation energy of ni-trogen in tantalum on plasma nitriding conditions was calculated according to the experimental data of hardness ofplasma-nitriding of tantalum vs time and temperature. The diffusion activation energy calculated belongs to (155.49±10.51)kJ/mol(783-983K). 相似文献
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Ti6Al4V钛合金表面Zr-N合金化层的抗高温摩擦磨损性能 总被引:1,自引:0,他引:1
为了改善钛合金的高温耐磨性能,采用锆-氮离子共渗与异步渗(渗锆后再氮化处理)两种工艺技术分别在Ti6A14V钛合金表面制备致密的锆-氮合金化改性层,对比研究了合金化层的组织结构特征和高温摩擦磨损性能.结果表明,两种工艺制各的Zr-N合金层表面均由ZrN相组成,异步渗改性层的内层则包含较厚的Zr-Ti固溶体,两种等离子表面合金化层均使钛合金表面硬度显著提高.同样温度和处理时间条件下,异步渗合金化层的厚度约为锆-氮共渗合金化层厚度的6倍,且氮化物层也较厚,原因归于前者处理过程中Zr与Ti之间良好固溶特性的充分发挥及ZrN相的扩散障作用的有效抑制.300℃高温下球盘摩擦磨损试验结果表明,由于锆-氮共渗合金化层深度较小,因而改善钛合金基材耐磨性能的效果相对较低.锆-氮异步渗处理则使Ti6A14V钛合金耐磨性能显著提高,摩擦因数降低50%以上,比磨损率降低2个数量级,原因归于该类合金化层高的表面硬度、大的层深、良好的高温抗氧化性能及优异表面承载能力的有机匹配. 相似文献
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4Cr2MoWVNi钢离子渗氮工艺研究 总被引:2,自引:0,他引:2
通过对4Cr2MoWVNi钢进行离子渗氮工艺处理,研究了温度、时间对渗层组织、耐磨性能的影响。结果表明,采用合适的处理温度和时间,可以得到最佳的渗氮层深及表面硬度,在保证一定的渗氮层深条件下,4Cr2MoWVNi钢的热耐磨性能明显提高,使模具使用寿命大幅度提高。 相似文献
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A series of experiments were carried out to study the influence of low temperature plasma nitriding on the mechanical properties of AISI 420 martensitic stainless steel. Plasma nitriding experiments were carried out for 15 h at 350℃ by means of DC- pulsed plasma in 25%N2+ 75%H2 atmosphere. The microstructure, phase composition, and residual stresses profiles of the nitrided layers were determined by optical microscopy and X-ray diffraction. The microhardness profiles of the nitridied surfaces were also studied. The fatigue life, sliding wear, and erosion wear loss of the untreated specimens and plasma nitriding specimens were determined on the basis of a rotating bending fatigue tester, a ball-on-disc wear tester, and a solid particle erosion tester. The results show that the 350℃ nitrided surface is dominated by c-Fe3N and ON, which is supersaturated nitrogen solid solution. They have high hardness and chemical stabilities. So the low temperature plasma nitriding not only increases the surface hardness values but also improves the wear and erosion resistance. In addition, the fatigue limit of AISI 420 steel can also be improved by plasma nitriding at 350℃ because plasma nitriding produces residual compressive stress inside the modified layer. 相似文献
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J. Michalski J. Tacikowski P. Wach E. Lunarska H. Baum 《Metal Science and Heat Treatment》2005,47(11-12):516-519
Results on the formation of a layer of γ′-nitride on the surface of carbon steel in the process of controlled gas nitriding (NITREG®) are presented. In the formation of single-phase layers of γ′-nitride it is necessary to control thoroughly the nitriding atmosphere including the stage when the treated material is heated to the process temperature. A mathematical formula relating the nitriding atmosphere with the value of the nitriding potential is suggested. Results of corrosion tests and metallographic studies of γ′-nitride layers are described. 相似文献