增强硫化橡胶与金属粘接的表面处理技术

表面处理是提高橡胶与金属材料粘接性能的重要工艺之一。介绍了目前用于硫化橡胶和金属表面处理的技术,如橡胶表面采用的硫酸法、氯化法、等离子体法、电晕放电法、UV及臭氧法等,金属表面采用的机械法、化学法、阳极氧化法等,提出了硫化橡胶与金属粘接表面处理技术的发展方向。     

功能性有机硅烷膜对金属腐蚀防护的研究现状及展望

功能性有机硅氧烷对金属表面进行处理是一种新型的表面防护处理技术,能够显著提高金属的耐腐蚀性能.介绍了功能性有机硅氧烷的结构和分类,探讨了功能性硅氧烷膜的腐蚀防护机理,总结了金属表面耐腐蚀性功能硅氧烷膜的研究现状和进展,以期对金属表面腐蚀防护提供指导和帮助.     

’93国际表面处理技术展览会在津结束

由天津市机械工业管理局、天津机械研究设计院和天津国际展览中心主办,德国格拉赫国际管理集团协办的'93国际表面处理技术、设备和产品展览会已于1993年11月16～20日在天津结束。国内外的60多个厂商参加了展览。参加展览的成果有:先进的金属表面成模技术、表面合金化处理技术、研磨、抛光技术、电镀技术、金属热喷涂技术、零部件表面耐磨和防蚀处理技术、涂装质量检测技术、金属清洗剂和防锈剂等。     

金属表面硅烷化技术概述

随着金属表面钝化处理工艺中环保要求的日益严格,表面硅烷化技术现已成为一种新型绿色表面钝化工艺,该工艺通过有机硅材料在金属表面形成高致密的保护膜而实施对金属的高效保护,本文结合最新研究进展,分别从保护机理、新型结构有机硅烷及最新应用领域方面阐述了该技术的特点和新动态。     

机械研磨金属表面纳米化的研究进展

在表面机械处理(SMAT)方式下,材料表面可以通过强烈塑性变形而实现纳米化,获得表面为纳米晶、晶粒尺寸沿厚度方向逐渐增大的梯度结构。表面纳米化可以使材料表面硬度提高且整体力学性能得到改善。同时材料表面活性得到极大地提高,为进一步化学处理提供良好的条件。从SMAT的基本原理、制备技术、纳米化机理、结构性能和化学处理等方面介绍了表面机械纳米化研究工作已取得的进展。     

选用GB/T 13911-1992<金属镀覆和化学处理表示方法>的原则

一、前言ＧＢ/Ｔ13911-1992《金属镀覆和化学处理表示方法》规定了金属镀覆和化学处理的表示方法,适用于金属和非金属制件上进行电镀、化学镀、化学处理和电化学处理的表示。对金属而言,若表面防护不当,就会使金属表面被锈蚀。金属的锈蚀在形式上有表面均匀锈蚀,表面局部锈蚀,或发生在金属内部的锈蚀。各种形式的锈蚀,都将使金属的机械、电气性能和表面质量受到严重的影响,从而降低设备的工作能力和使用寿命,严重的甚至报废。因此,金属表面的防护是一项很重要的工作。ＧＢ/Ｔ13911-1992标准对镀覆的表示方法、标注阐述得很清楚,本文就该标准…     

泡沫金属结构对池沸腾换热特性的影响

本文实验研究了制冷剂在不同结构泡沫金属表面的池沸腾换热特性。测试样件为泡沫铜,样件结构涵盖不同的孔密度(5～40 PPI)、孔隙率(0. 90、0. 95)与厚度(4～8 mm)。实验结果表明,孔密度为40 PPI泡沫金属比5 PPI泡沫金属最大表面传热系数提升了26. 4%;随着厚度增大,泡沫金属池沸腾换热先增强后减弱;孔隙率为0. 90泡沫金属比0. 95泡沫金属最大表面传热系数高13. 2%。根据实验结果,开发了制冷剂在不同结构泡沫金属表面池沸腾传热关联式,关联式与95%实验数据的误差在±30%以内,平均误差为12. 2%。     

硅烷偶联剂在金属表面预处理中的应用研究进展

近年来发展的硅烷偶联化预处理技术因其对环境友好、可操作性强,有望成为金属表面铬钝化处理的替代工艺。硅烷膜作为金属表面预处理层,不但改善了基材表面的状态,增强了涂料与基材间的黏附性能,也可作为单独的防护涂层,对腐蚀介质的渗透起着物理屏障作用。主要从3个方面介绍了硅烷偶联剂在金属表面预处理中的研究进展:(1)金属表面硅烷偶联化机理;(2)金属基材表面状态、硅烷水解体系、硅烷成膜方式及膜固化方式等工艺对膜性能的影响;(3)硅烷预处理技术研究的新进展,包括传统浸渍成膜、电沉积辅助法制备硅烷膜及无机稀土金属盐、纳米颗粒、缓释剂掺杂制备的硅烷杂化膜的研究现状。     

CPJ──1型超声波抛光机

一、概述: 超声波抛光机是利用它所产生的高频机械振动对金属模具进行抛光,它首先将市电转变成超声波频率的交流电,通过压电陶瓷将其转变为超声波机械振动,利用工具头对金属进行抛光,省时、省力、精度高,可提高工效若干倍。 二、应用 1.对注塑模,压铸模,冲压模,(包括超硬度的)铸模,及机器表面进行研磨处理和镜面抛光、简便、易行、速度快。 2.去除和抛光放电机械沉积的硬化层。 3.快速精确地研磨线切割放电机械和研磨机械的表面。 4.无论是非铁材料还是超硬金属、无论其硬度或形状,它都能有效地将粗糙的金属表面研磨成镜面。 三、主要技术指…     

硅烷偶联剂在防腐涂层金属预处理中的应用研究

使用硅烷偶联剂对金属进行预处理是新兴的、环保型的表面处理工艺,可使涂层的附着力及耐蚀性能显著提高,可替代传统的磷化和钝化处理.本文对SCA的结构、作用机理,SCA的选择、溶液的制备,金属表面硅烷化处理,有机硅烷薄膜及其分析测试做了简要阐述.     

Application of the local strain approach on a rolling point contact model

A newly developed cold forming process, the linear flow splitting process, allows the bifurcation of thin metal sheets by severe plastic deformation (SPD). This process produces flanges with an ultra-fine grained (UFG) microstructure, which is characterized by an increased hardness and lower surface roughness in comparison to the material in as-received state. The technology is researched within the Collaborative Research Centre 666 (CRC 666) “Integral Sheet Metal Design with Higher Order Bifurcations”. The increased hardness and reduced surface roughness of the flanges make this technology suitable for manufacturing linear guide rails. In order to achieve the required reliability and fatigue strength, the assessment of the performance of the linear flow-split profiles with gradient microstructure is of great importance. When considering rolling contact fatigue, the examination of the mechanical behavior of the side of the flange with higher hardness due to the UFG microstructure is required. In order to reduce time and costs, a numerical method to determine the rolling contact fatigue behavior would be useful minimizing the normally applied experimental effort. The present work aims to check the applicability of the local strain approach for the evaluation of the rolling contact fatigue behavior of linear flow split components by a Finite Element (FE) analysis. The Hertzian theory is only valid for homogeneous materials and cannot be directly applied to the flanges with gradient microstructure. Therefore an accurate modeling of the material in order to take into account the gradient in the mechanical properties is required. In this paper the characterization of the material behavior under axial cyclic loading will be presented. These results will be used for the Bergmann damage parameter to analyze the rolling contact fatigue behavior. Some parameters required for the application of the Bergmann approach are determined by a numerical simulation of the rolling contact. Results are compared to rolling contact fatigue tests performed on a recently developed test rig under the assumption of rolling without sliding and neglecting the effect of surface roughness and residual stresses.     

Effect of tube spinning and subsequent heat treatments on strength,microstructure and residual stress state of AISI/SAE type 4140 steel

Abstract

In the present study, the effects of deformation percentage (23, 30, 50 and 66%) and subsequent stress relief and tempering heat treatments on the mechanical properties, residual stress state and microstructure of AISI/SAE type 4140 steel tubes manufactured by forward spinning were evaluated. Mechanical properties were determined by means of hardness and tensile tests. The tangential component of the surface residual stresses was determined by a slitting method. Plastic deformation of the metal during spinning refined and elongated the grains in the direction of metal flow, following a spiral path, resulting in improved mechanical properties. Tensile and yield strengths, as well as hardness, were all increased as a function of increasing percentage deformation. With stress relieving, the strength values were enhanced, whereas a slight decrease in hardness took place. Stress relieving did not change the microstructure considerably, whereas tempering resulted in a partially recrystallised microstructure, removing the effect of plastic deformation. The tangential residual stresses were tensile, and those of the as deformed tubes increased with an increasing amount of deformation up to 50%, then tended to decrease. The magnitude of the residual stresses decreased with stress relieving heat treatment, while tempering reduced the residual stresses to negligible levels.     

Ti2AlNb合金构件全流程模拟及组织性能预测

金属构件的塑性加工不仅需要控制其形状尺寸,还要调控其微观组织和力学性能,以获得满足服役要求的产品。构件成形结束后,常需要通过热处理工艺调控其组织和性能,但由于成形过程中的变形参数影响其热处理前的微观组织,因此,也影响到其热处理过程的组织演变,进而影响构件的服役性能,导致热处理调控更加复杂。本文基于机器学习的方法,考虑变形参数对热处理的影响,建立了Ti₂AlNb合金构件高温成形过程微观组织和力学性能的预测模型,并与有限元模拟软件结合,建立了Ti₂AlNb合金构件成形-热处理的全流程模拟方法。本文通过该方法对Ti₂AlNb管材高温压制-时效处理工艺进行了全流程的模拟,模拟结果表明变形和热处理参数均会对成形构件的组织和力学性能产生影响。进而通过成形和热处理实验对模拟结果进行了验证,模拟结果与实验结果的一致性较好。说明通过该方法,可以实现构件成形-热处理全流程的模拟和组织-性能预测,可用于指导加工工艺的制定。     

Introducing a hierarchical structure for fabrication of a high performance steel

The multifunctional diversities existing in nature provide clues to speculate the structure–property–function relationships. A hierarchically structured steel is designed by using principles derived from nature and fabricated in situ by a one-step method of surface mechanical attrition treatment (SMAT). The microstructure of the processed steel is characterized by multilayered structure with hard nanocrystalline surface and compliant inner-layer, in particular with a smooth mechanical gradient induced by dual-phase constituents and multiscale grain size distribution. The hierarchically structured steel exhibits simultaneously high stiff, strong and large ductility, which originate from the joint deformation mechanisms of distinct reinforcing layers. The four layers present their own unique deformation mechanisms, including second-phase hardening, transformation induced plasticity and twin strengthening. The unique spatial form of gradation can release stress concentration and improve energy-dissipation leading to exceptional mechanical properties compared with the uniform materials.     

搅拌摩擦沉积增材技术研究进展EI北大核心

搅拌摩擦沉积增材(additive friction stir deposition,AFSD)技术是一种新兴固相增材制造技术,采用金属棒材、粉材、丝材为增材材料,增材过程中依靠增材材料与板材摩擦产生摩擦热以及材料剧烈变形产生的塑性变形热形成黏塑性沉积层,沉积层逐层堆积形成三维实体结构件;基于其固相特征,具有熔覆增材技术不可比拟的优势,目前已成为增材制造领域的研究热点。本文从设备研制、微观组织演变、材料流动特性、力学性能变化四个方面综述了AFSD技术最新国内外研究进展;分析了该技术应用于工程实际的可行性,展望了在增材制造、材料修复、零件加固、制造金属涂层领域的应用前景;最后指出了产热机制、材料流动特性、辅助优化工艺、智能化设备研制等为未来的研究方向。     

SHS复合管FeNi合金过渡层接合界面结构及力学性能

采用离心分离自蔓延技术,制备出了一种新型的具有FeNi舍金过渡层的Fe-Cr-Ni-Al2O3金属间化合物梯度复舍管。研究分析了舍金过渡层与金属基体接舍界面组织结构。结果表明,梯度过渡层的组织形态为细小的柱状晶-胞状树枝晶-树枝状晶。结晶初期,界面处液态金属依附于半熔化状态基体金属的晶粒表面,以细小的柱状晶的形态沿径向向钢管中心联生生长,形成牢固的冶金结舍;梯度结构及树枝状交叉织构,提高了陶瓷内衬与基体的结合强度,使复合管内衬层具有良好的力学性能。     

锅炉水冷却管爆裂原因分析

通过宏观检查、金相检验、化学成分及能谱分析等方法对锅炉水冷却管爆裂原因进行了分析。结果表明:爆裂处管子局部受热,导致显微组织发生变化,使钢管金属材料的力学性能下降,受热面变形,管子慢慢胀粗导致管壁减薄,引起管子鼓包、穿孔直至开裂,造成爆管。     

Strain-induced formation of a gradient nanostructured surface layer on an ultrahigh strength bearing steel

In the present work, an ultrahigh strength bearing steel(AISI 52100) was subjected to surface mechanical rolling treatment(SMRT) at room temperature. Microstructural observations showed that martensitic laths, twins and cementite particles in the initial microstructure underwent distinct plastic strains and were gradually refined into nanostructures. Consequently, a gradient nanostructured(GNS) surface layer with a mean grain size of ~24 nm at the top surface was obtained on the bearing steel, resulting in an increment of ~20% in the surface hardness. Analyses based on microstructural evolution, phase constitution and in-depth hardness distribution revealed a mechanically induced formation mechanism of the GNS surface layer. The multiple surface severe plastic deformation under fine lubrication and cooling during SMRT contributed to the formation of a thick hardened surface layer on the bearing steel.     

5083铝合金搅拌摩擦焊接头的显微组织与力学性能

对8 mm厚5083-H321铝合金板进行了搅拌摩擦焊接试验,研究了焊接工艺参数对搅拌摩擦焊接头显微组织和力学性能的影响。结果表明:该搅拌摩擦焊接头焊核区显微组织为细小的等轴晶组织,热机影响区为拉伸弯曲变形组织,热影响区非常窄,其晶粒尺寸与母材相当;综合接头表面形貌和拉伸性能得到较佳的搅拌摩擦焊接工艺参数为使用搅拌针为三棱形带螺纹、轴肩为内扣型的搅拌头,主轴转速为300 r·min^-1,焊接速率为120 mm·min^-1;在该工艺条件下接头表面成形良好,抗拉强度可达到母材的94.5%。