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迅速崛起的激光表面处理技术   总被引:7,自引:0,他引:7  
陈炳贻 《表面技术》1997,26(1):31-33
激光表面处理技术正在不断扩大其工业应用范围-激光表面相变硬化,包覆,熔化和合金化之类的表面处理工艺和来改善材料的表面性能。而了近的UV激光的进展拓开了这一技术的应用范围并增加了灵活性,这包括表面结构的改善,增加粘着和结合能力以及激光物理气相沉积,激光化学气相沉积等。此文扼要地阐述了这些工艺过程,可能的应用区域及其优点。  相似文献   

3.
不锈钢表面氧化皮的清除   总被引:10,自引:0,他引:10  
不锈钢应用很广.但不锈钢并非绝对不锈,当不锈钢经各种加工处理后表面存在未除去的氧化皮或氧化痕迹时,其耐蚀性会大大降低.对于尚需进行下一道工序加工的不锈钢,这些氧化皮还将影响下道工序的质量.因此,有必要将不锈钢表面的氧化皮或氧化痕迹清除干净.本来,使金属表面形成一层氧化膜是防止金属表面进一步腐蚀的措施之一,因为这层氧化膜能对金属起到保护作用.但是,氧化膜保护性的好坏,首先取决于膜的完整性;其次,还受膜的晶体结构、电子结构及力学性能的影响.不完整的氧化膜使金属表面电化学腐蚀加快.氧化膜中新的氧化物的形成,由于体积差异,会在金属表面产生新的应力;氧化物与基体的热膨  相似文献   

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1引言热喷涂是把材料加热到格融或半格融状态以高速度喷射到基体表面上,形成具有希望性能的膜层,从而达到对基体表面改质目的的表面处理技术。在诸多的表面改质方法中,热喷涂法具有许多独特的优点,诸如:(l)可用于各种金属、陶瓷、高分子等材料的表面改质;(2)可供喷涂  相似文献   

6.
日本表面技术研究状况与发展动向一瞥   总被引:4,自引:0,他引:4  
邸柏林 《表面技术》1993,22(1):44-48
简要地论述日本在电镀、化学镀、热喷涂及真空镀等表面技术方面的研究状况和发展动向,以及笔者从中得到的几点粗浅认识和感受。  相似文献   

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表面工程学研究   总被引:8,自引:0,他引:8  
全面介绍了一门新兴学科-表面工程学的形成、内涵、研究现状与发展趋势,以期引起一番讨论和领导的重视。  相似文献   

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范晴  范宗荣 《腐蚀与防护》2000,21(3):117-118
金属表面涂镀、防护前必须进行表面清理 ,将表面的污垢、铁锈及油漆层等附着物清除干净。除锈越彻底 ,防腐蚀效果就越好。大量实践证明 ,防腐蚀质量主要取决于金属表面的清理质量 ,作用比例约占50 %。目前国内常用的清洗方法如手工清除、化学清除和机械清除 (干喷砂、喷丸 )等工艺均难于达到Sa3级高质量表面水平 ,又存在环境污染、效率低、能耗高、设备庞大及劳动条件恶劣等弊端。为此 ,昆明大光明清洗防腐公司发明了一种新型表面清理机 ,分两种型号 :水砂型 (专利证号 ZL972 2 930 0· 0 )及气砂型 (专利证号 ZL992 31 0 50· 4)为清洗工…  相似文献   

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三谷景造 《模具技术》1991,(4):48-52,47
前言目前广泛要求对注塑模表面进行处理,其目的有去除电加工表面硬化层,为提高产品附加值而对模具表面施行的装饰纹加工,还有的是为了提高模具的生产效率而采取的更为切实的加工手段等。这三方面都是以和保证提高质量,提高生产率、操作性和耐用性为目的而进行处理的。本文对此作一叙述。 1.表面处理的目的最近,随着注塑成形产品适用范围的扩大及代替金属的塑料产品增加,在改进塑料性质和加深开发的同时,复合强化塑料正在得到越来越广泛的应用,并要求具有更高的精度。产品  相似文献   

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模具表面改性新技术--金属用离子注入   总被引:1,自引:0,他引:1  
《模具制造》2002,(3):57-57
早在1952年,美国贝尔实验室已经开始研究用离子束轰击技术来改善半导体特性,六十年代,半导体器件生产的水平进一步提高,迫切要求寻找新的方法研制一些特殊用途的新型器件,于是兴起了离子注入技术。近20年来,在微处理机和计算机存储器的集成电路基片生产中,离子注入已经是半导体材料的一种标准掺杂方法,离子注入方法的可靠性、可控性和重复性使得这项工艺成为半导体工业的支柱。在20世纪60年代中期,英国科学家探索了离子束对金属的作用。他们早期的努力集中于离子注入技术对金属材料的摩擦和显微硬度的影响,但不久就转向…  相似文献   

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建立了前混合磨料水射流喷嘴物理模型。基于FLUENT软件,采用颗粒轨道模型、Grant弹性恢复系数和E/CRC磨损模型对磨料水射流喷嘴内的磨损特性进行了数值模拟。结果表明:当喷嘴收缩角为20°以上时,喷嘴磨损呈现两个严重磨损区,分别在喷嘴圆柱段入口处前较短距离范围内和喷嘴圆柱段出口处前较短距离范围内;随着喷嘴收缩角的增大,磨料颗粒与喷嘴圆柱段壁面碰撞次数和速度增加,同时随着喷嘴长径比的增大,喷嘴圆柱段壁面磨损速率整体增加,严重磨损区范围扩大,结果均使喷嘴圆柱段的磨损加剧。以喷嘴壁面磨损速率的面积加权平均积分表征喷嘴整体的磨损程度。随着收缩角和长径比的增大,喷嘴壁面磨损速率的面积加权平均积分增大,喷嘴的磨损整体而言越严重。因此,从减小喷嘴磨损的角度而言,喷嘴的收缩角和长径比宜取小值。  相似文献   

12.
旋轮参数对铝合金分形旋压的影响规律   总被引:2,自引:2,他引:0  
铝合金分形旋压是一个复杂的多因素耦合影响的塑性成形过程,研究其旋轮参数对成形过程的影响可为相关成形参数的确定和优化设计提供理论依据。基于建立的可靠的铝合金分形旋压三维有限元模型,文章研究揭示了旋轮分形角、旋轮圆角半径、旋轮轴向进给比等旋轮参数对成形过程中的切向拉应力、周向压应力以及成形凸缘的不均匀变形程度和最终壁厚偏差的影响规律。结果表明,增大旋轮分形角,可以消除旋轮前方的金属堆积和降低成形过程中坯料开裂失效的可能性,可以使得成形凸缘的不均匀变形程度减小和成形精度降低;旋轮圆角半径的改变,对消除旋轮前方的金属堆积和降低成形过程中坯料开裂失效的可能性影响并不明显,但增大旋轮圆角半径,可以使得成形凸缘的不均匀变形程度增大和成形精度升高;旋轮轴向进给比的改变,对消除旋轮前方的金属堆积和成形凸缘的成形精度的影响并不明显,但增大旋轮轴向进给比,可以降低成形过程中坯料开裂失效的可能性,可以使得成形凸缘的不均匀变形程度减小。  相似文献   

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Ion-plasma sputtering and the codeposition of ultradisperse particles of Ta and Al have been used to prepare solid solutions in the entire range of concentrations of the binary system in the form of alloy coatings. The formation of the solid solution of these alloys directly in the process of codeposition confirms the theory of the thermofluctuation melting of small particles and coalescence of quasi-liquid clusters of subcritical size. Upon the formation of coatings via the deposition of nanolayers of tantalum of less than 0.8 nm for β-Ta and 1.1 nm for Al, the spontaneous mutual dissolution of the components occurs with the formation of solid solutions of one metal in the other. Beginning with a concentration of ~85 at % Al in the alloy, Al atoms control the type of symmetry of the arising lattice. An increase in the characteristic dimensions (thickness of sublayers) of tantalum and aluminum leads to the appearance of solid solutions of these metals in these coatings in addition to the β tantalum and aluminum phases, as well as of amorphous regions and superlattices formed by nanoclusters of one metal in the matrix of the other. It has been established that the formation of these superlattices is controlled by the size factor.  相似文献   

14.
大块涂层缺陷对碳钢腐蚀特性及阴极保护效果的影响   总被引:1,自引:0,他引:1  
采用了环氧煤沥青作为涂层材料,研究了大块涂层缺陷对碳钢腐蚀特性及阴极保护效果的影响,测定了具有面积比例为4.91%大块涂层缺陷的Q235钢于3.5%NaCl水溶液中的交流阻抗谱.结果表明,随着浸泡时间的延长,在自然腐蚀电位下,存在剥离涂层缺陷时碳钢的腐蚀程度高于破损涂层缺陷时碳钢的腐蚀程度;在阴极极化条件下,具有剥离涂层缺陷的碳钢阴极保护效果随时间延长逐渐降低直至最后消失,而具有破损涂层缺陷时阴极保护效果随时间延长优于剥离涂层缺陷;电解质溶液向涂层内部的渗透以及涂层缺陷与钢基体间的缝隙腐蚀是导致具有大块涂层缺陷碳钢腐蚀的主要原因.  相似文献   

15.
The thermodynamic properties of alloys of the Ge-Mn system are analyzed. Concentration dependences of thermodynamic mixing functions are obtained with the use of adequate published data. The variation of the heat capacity during the dissolution of manganese in melts of Ge-Mn is estimated using the temperature dependence of the partial enthalpy of mixing of manganese. Partial excess entropies of mixing are computed with the use of partial entropies of mixing obtained by the method of calorimetry and of partial excess entropies of mixing measured by the method of electromotive forces. Integral thermodynamic functions of mixing are computed from the corresponding partial quantities.  相似文献   

16.
The results of investigations of the effect of the regulated parameters of low-frequency modulation on the characteristics of deposited beads in reconditioning of the working surfaces of dies of stamping tools are presented. The effect of the frequency and duty ratio of the modulated conditions on the mechanical properties of the deposited layer and the structure of its metal is described. Recommendations are issued for the effective application of technology with the controlled modulated conditions in the reconditioning of the working edges of the dies of the stamping tools.  相似文献   

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Abstract

The paper is devoted to 100th anniversary of the outstanding Russian scientist professor Yuriy Mikhailovich Lakhtin – the founder of the world-famous scientific school of surface strengthening of metals and alloys. Lakhtin's scientific school is recognised for its contribution into research of processes of thermochemical treatment of metals and especially of nitriding. Today at the Department of Metal Science and Heat Treatment of MADI his followers continue the traditions of Lakhtin's scientific school. The development of technologies of surface engineering is based on complex modelling of physical processes realised by thermochemical treatment of metals. Thermodynamic models describe the interaction between metals and components of saturating atmosphere and predict phase composition of diffusion layer. Diffusion models of kinetics of saturation of metals allow us to calculate the rate of growth of diffusion layer and regulation of its depth and structure. Structural models determine quantitative dependence between parameters of structure (grain size, dispersed particles, etc.) and mechanical properties. These models allow us to estimate the level of strengthening by control of structural specifics of strengthened layer. On the basis of this complex of models, new efficient technologies of surface strengthening are developed.  相似文献   

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Changes in the potential energy of atoms that constitute the nearest neighborhood of vacancies formed in the bulk of d transition and precious cubic metals have been determined. These changes agree with the available first-principles calculations of changes in the potential energy of atoms of the nearest neighborhood of vacancies. In the cores of crystallite-conjugation regions (CCRs) of bcc polycrystalline d transition metals, the formation of vacancies is accompanied by positive changes in the potential energy of atoms of their nearest neighborhood. The absolute magnitudes of these changes are several times less than the changes in the potential energy of atoms of the nearest neighborhood of vacancies in the bulk of these metals, in accordance with the relationship between the enthalpies of formation of vacancies in these regions of polycrystals. The changes in the potential energy of atoms of the nearest neighborhood of vacancies formed in the cores of CCRs of fcc polycrystalline metals are negative because of the split structure of vacancies in the CCR cores of such metals.  相似文献   

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Conclusions Investigations of the mechanical and physical properties of metals at different loading rates and temperatures confirmed the existence of two types of hardening which differ in their physical nature — dislocation-substructural and diffusion.Diffusion hardening is practicable under conditions of programmed loading in which the rate of increase of external stress equals the rate of diffusion transfer of lattice defects. The structure of metals hardened by programmed loading is more uniform and mechanically more stable with respect to the original as the result of diffusion redistribution of point and line defects, pinning of dislocations, and the removal of local stress concentrations because of microplasticity, leading to release of dislocation pile-ups and their movement to the boundaries. The elimination of weak places with stress concentrations and the removal of structural heterogeneities (regions of potential nucleation of brittle cracks) after programmed loading is indicated by the uniform distribution of slip traces, improvement of the plastic properties, reduction of the static cold brittleness threshold, suppression of the Bauschinger effect, etc. The existence of the effect of programmed hardening in pure metals, the increase of the resistance to deformation without reduction of the plasticity, an improvement of the plastic properties for some metals, little change in the internal friction of iron in the temperature region of the carbon peak, and other results of the investigation indicate the fundamental difference between the mechanism of programmed hardening and ordinary age-hardening.The distinguishing characteristics of the method of programmed hardening are the increased resistance to deformation and simultaneous improvement of the combination of physical properties, the higher margin of plasticity, the stability of the microstructure with respect to recrystallization, the attainment of hardening with very small remanent strain (0.01–0.5%).Physicotechnical Institute of the Academmy of Sciences of the UkrSSR. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No.5, pp.2–8, May, 1967.  相似文献   

20.
Conclusions Damping in high-chromium ferritic steels is formed primarily as the result of magnetoelastic dispersion of energy, the level of which is determined by the character of interaction of the magnetic domain boundaries moving in the field of applied cyclic stresses with some subsystems of stoppers, defects of the crystalline structure. The maximum in damping capacity of Kh16, Kh16M4, and Kh25 steels is observed after annealing at 900–1000°C and is the result of superposition of individual oppositely acting on the magnetic constituent of damping contributions during evolution of structural defects under different temperature-time actions. An analysis of the contribution of different crystalline lattice defects makes it possible to predict the path of formation of the controlled level of vibration absorbing properties of high-chromium steels. The high-damping condition is characterized by a low level of internal stresses, moderate values of coercive force, and non-linearity of the elastic properties under the action of external stresses. The damping capacity after annealing in the temperature area of stratification of high-chromium ferrite and appearance of 475°-brittleness is determined by the action of two primary tendencies, the reduction of internal stresses as the result of ecomposition of the supersaturated solid solution of interstitial impurities and the subsequent increase in them as the result of stratification of high-chromium ferrite and formation of zones enriched with chromium.Moscow Institute of the Physics of Metals. Kharkov State University. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 9, pp. 29–34, September, 1993.  相似文献   

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