颗粒增强铸造金属基复合材料

介绍了国内外对金属基复合材料的研究及应用的简单情况,重点阐述了石墨、碳化硅颗粒增强金属基复合材料的制备及其特性,以及SiCp／ZL109复合材料在175柴油机活塞上的台架试验结果。展望了铸造颗粒增强金属基复合材料的应用前景。     

颗粒增强钛基复合材料在汽车工业上的应用

金属基复合材料可分颗粒增强及纤维增强两种类型．颗粒增强金属基复合材料（ＰＭＭＣｓ）有望在近期得到广泛应用,这是由于颗粒增强金属基复合材料的价格／性能之比,远远低于纤维增强金属基复合材料。１ＰＭＭＣｓ的发展状况 熔化金属混合工艺将是生产ＰＭＭＣｓ最经济的路线之一。用该方法生产的Ａｌ基、Ｍｇ基、Ｔｉ基复合材料铸锭,利用常规的加工工艺,即通过轧制、挤压、锻造等手段可以加工成各种复合制品。目前挪威的ＮｏｒｓｋＨｙｄｒｏ公司已具备通过熔化金属混合工艺达到 １５０ｔ／ａ金属基复合材料的生产能力。 Ａｌｃａｎ公…     

金属基陶瓷颗粒增强复合材料的制备方法

介绍了金属基陶瓷颗粒增强复合材料(metal matrix ceramic reinforced cornposites)的基体与陶瓷增强相的选择,同时指出如何有效地改善金属基体与陶瓷颗粒增强相之间的浸湿性问题.总结了烧结前期复合坯体的一些主要制备方法.又介绍了金属基陶瓷复合材料(MMC)的烧结工艺,重点介绍了通电烧结,比较了各新工艺的基本原理和优缺点,最后对金属基陶瓷颗粒增强复合材料进行了技术展望.     

非连续相混杂增强金属基复合材料的研究进展

论述了非连续增强金属基复合材料的研究概况,简要介绍了非连续相混杂增强金属基复合材料常用的几种制备方法,包括搅拌熔铸法、压力铸造法、无压浸渗法、喷射沉积法、粉末冶金法、原位反应法等,同时对常见的3种增强体的混杂类型:颗粒+颗粒、短纤维+晶须(短纤维)、颗粒+晶须(短纤维)增强金属基复合材料的性能和国内外研究现状进行了综述,指出了非连续相混杂增强金属基复合材料存在的问题,并对其今后的发展进行了展望。     

基于SPD法颗粒增强铝基复合材料研究综述

简单介绍了利用几种大塑性变形工艺(Severe plastic deformation)制备颗粒增强铝基复合材料的研究概况,叙述了等径角挤压法、高压扭转法、挤扭法制备颖粒增强铝基复合材料的国内外研究现状,并对今后大塑性变形方法制备颗粒增强金属基复合材料的发展进行了展望.     

可在导弹制导系统中取代铍的新型金属基复合材料

美国Arco先进材料公司金属复合材料部,采用自己研制成的碳化硅增强铝合金,通过精密锻造工艺制成了导弹制导系统的惯性测量装置用仪表盖。使碳化硅增强铝合金被命名为SXA工程材料。据称,这是金属基复合材料在导弹制导系统中的首次大规模应用,碳化硅增强铝合金的使用标志着金属基复合材料的开发和实用化的一个重大的里程     

陶瓷增强金属基复合材料的研究进展

介绍了陶瓷增强金属基复合材料研究的最新进展。研究了陶瓷增强剂的性能、复合材料的先进制备技术、各种金属基复合材料的性能和应用，以及复合材料研究中存在的问题和今后的发展趋势。     

原位自生金属基复合材料的制备方法

介绍了原位自生金属基复合材料的性能,概述了几种原位制备颗粒增强金属基复合材料(MMCs)的方法:包括自蔓延高温合成法(SHS)、弥散放热法(XD法)、直接反应法(DRS)、混合盐反应法、接触反应法、反应喷射沉积法、反应挤压铸造法、VLS法等.最后指出要达到工业生产应用,还需要解决的一些难题,并指明了今后的研究方向.     

非连续增强金属基复合材料及其在汽车工业的应用

介绍了金属基复合材料及其制造方法，重点讨论了搅拌法工艺，概述了颗粒增强铝基复合材料在汽车工业的应用。     

SiCp/Al复合材料切削加工性的影响机理研究

针对SiCp/Al复合材料,探究了颗粒尺寸对其切削加工性的影响机理.基于ABAQUS有限元仿真软件建立了不同颗粒尺寸的SiCp/Al复合材料仿真模型,并通过单因素实验,探明了颗粒尺寸在不同切削参数下对切削力、切削温度以及切屑形态的影响规律,得到了刀具-颗粒相对位置对已加工表面的影响规律.研究结果表明:当颗粒尺寸从10μ...     

Damping behavior of discontinuously reinforced ai alloy metal-matrix composites

High damping materials allow undesirable mechanical vibration and wave propagation to be passively suppressed. This proves valuable in the control of noise and the enhancement of vehicle and instrument stability. Accordingly, the scientific community is continually working toward the development of high damping metals (hidamets) and high damping metal-matrix composites (MMCs). The MMCs are particularly attractive in weight-critical applications when the matrix and reinforcement phases are combined to provide desirable property combinations, such as high damping and low density. Inspection of the available scientific literature, however, reveals that an understanding of the precise correlation between the presence of secondary phases (either reinforcements or precipitates) and material damping has eluded investigators, partly as a result of the superposition of multiple mechanisms. As a step toward the clarification of damping phenomena in discontinuously reinforced MMCs, this article describes the damping behavior and mechanisms that are present in discontinuously reinforced MMCs, with particular emphasis on particulate-reinforced Al alloy MMCs processed using spray atomization and deposition. The operative damping mechanisms in the particulate-rein-forced MMCs are discussed in light of the data obtained from microstructural studies and damping capacity measurements. This article is based on a presentation given in the Mechanics and Mechanisms of Material Damping Symposium, October 1993, in Pittsburgh, Pennsylvania, under the auspices of the SMD Physical Metallurgy Committee.     

金属基复合材料的发展及其应用

金属基复合材料是近几年来复合材料研究中的热点.文章综述了金属基复合材料的分类、性能特点、制备方法,总结了其主要进展及应用.     

Directionally Constrained Viscoplasticity for Metal Matrix Composites

A theoretical framework along with an experimental comparison and numerical simulation is presented, for the modeling of the viscoplastic behavior of metal matrix composites (MMCs). MMCs are finding increasing applications in aerospace structures. MMCs have strong directional properties that directly influence the evolution of the internal variables, namely, the backstress and viscoplastic strain. The model is developed within a micromechanical framework for MMCs using the equilibrium surface approach. The directional properties of MMCs are incorporated by proposing a constrained equilibrium surface, which is based on the constrained stress terms proposed. The micromechanical framework combines the viscoplastic properties of the matrix with the elastic properties of the fiber. Model-generated experimental comparisons and simulations are also presented.     

A Phenomenological Model for Tool Wear in Friction Stir Welding of Metal Matrix Composites

Friction stir welding (FSW) of metal matrix composites (MMCs) is advantageous because the solid-state nature of the process precludes formation of deleterious intermetallic phases which accompany melting. FSW of MMCs is complicated by rapid and severe wear of the welding tool, a consequence of contact between the tool and the much harder abrasive reinforcement which gives the workpiece material its enhanced strength. The current article demonstrates that Nunes’s rotating plug model of material flow in FSW, which has been successfully applied in many other contexts, can also help us understand wear in FSW of MMCs. An equation for predicting the amount of wear in this application is developed and compared with experimental data. This phenomenological model explains the relationship between wear and FSW process parameters documented in previous studies.     

数控加工技术在钎具生产中的应用实例

随着社会经济的不断发展,国内制造业水平也在不断的提高,机械加工技术得到了很大提升,数控技术已逐渐成为国内机械加工中的主要技术,数控技术在机械加工技术中的应用可有效提高机械加工中对机床设备的控制,数控技术在实践运用时取得了一定的成果。本文主要通过数控加工技术在钎具加工生产中的应用实例,对数控技术在机械加工中的应用进行了分析和探讨。     

西门子 PLC400控制系统在辊底式淬火炉中的应用

金属在加工过程中需要经过精细的工艺过程,淬火技术是金属淬炼加工过程中的一项基本工艺过程。辊底炉作为淬火过程中必备的应用设备之一,在我国金属加工制造业的发展中起到了巨大的促进作用。对于现有加工制造业的加工技术手段,辊底炉的出现有效提升了金属冶炼制造过程中的技术手法。在辊底式淬火炉研发制造的过程中,使用西门子PLC400系统对整个淬火过程进行控制,将有助于提升其对金属加工过程的处理能力。     

Role of bile acids in duodenal migrating motor complexes in dogs

Previous studies have suggested that enterohepatic circulation of bile acids is essential for regular cycling of duodenal migrating motor complexes (MMCs). The present study was an attempt to clarify the role of bile acids in the enterohepatic circulation system in initiating duodenal MMCs. Seven dogs underwent total external biliary diversion that resulted in the loss of MMCs originating from the duodenum. Sodium ursodeoxycholate (6 mg/kg/hr) was then given either through the portal vein or a peripheral vein, and motility of the gastrointestinal tract was serially recorded. When sodium ursodeoxycholate was given either through the portal vein or a peripheral vein during external biliary diversion, duodenal MMCs restarted. The cyclic change in plasma motilin levels during an MMC cycle as induced by sodium ursodeoxycholate was almost the same as in a normal MMC cycle. Total bile acid concentration in the portal vein changed cyclically with MMC cycles when bile flow was intact but did not change cyclically with MMC cycles restarted by intravenous bile salt infusion. Bile acid stimulation of putative receptors existing between the portal vein and intrahepatic bile ducts may be involved in initiating normal duodenal MMC cycles.     

精密异型孔型轧辊精加工的特殊方法

介绍了精密异孔型轧辊精加工的二种方法,其一是采用仿形削装置车削砂轮进行磨削精加工,其二是采用超硬车刀对淬火后的轧辊进行精车实现以车代磨。     

Impact of Volume Fraction and Size of Reinforcement Particles on the Grain Size in Metal–Matrix Micro and Nanocomposites

In metal–matrix micro and nanocomposites (MMCs and MMNCs), the presence and interactions of various strengthening mechanisms are not well understood, but grain boundary strengthening is considered as one of the primary means of improving the yield strength of composites. Owing to the importance of grain size on mechanical properties, it is necessary to be able to describe how incorporation of nanoparticles (NPs) in both powder metallurgy (PM) and solidification processing (SP) affects this critical property. In the present work, we provide a basis for an empirical equation that relates particle fraction and particle size to MMNC grain size for both PM and SP synthesis methods. The model suggests that NPs retard grain coarsening in PM MMNCs and also seems to describe the effect of reinforcement concentration on grain size in SP MMCs and MMNCs.