碳化硅颗粒增强铝基复合材料

在无外加压力或真空的大气条件下制备碳化硅颗粒增强铝基复合材料,该工艺以Ｋ２ＴｉＦ６为助渗剂,使其与碳化硅颗粒均匀混合,在浸渗用的铸模中制成混合全,由液奢望 铝或其合金自动浸渗制备碳化硅颗粒增强的铝基复合材料ＳｉＣｐ／Ａｌ。分析了影响工艺过程的若干因素,指出用该工艺制备复合材料的可能性,并对浸渗机理进行了探讨 。     

陶瓷/金属复合材料制备工艺及实验装置设计

介绍了真空压力浸渗工艺制备陶瓷/金属复合材料的工艺原理,并就真空压力浸渗法制备复合材料工艺过程的影响因素进行了动力学分析,给出了渗透时间、温度及预制体高度、纤维含量和纤维直径等工艺参数的定量关系。设计了一套便捷实用的小型实验装置,巧妙采用底注式真空系统、双层不锈钢壳体结构和可拆卸式联接件使得实验装置结构简化,实用方便。     

多孔C_f/A复合材料的制备与性能

通过硝酸铝饱和溶液循环浸渗热解制备了 C纤维编织体增韧多孔氧化铝陶瓷基复合材料 (Cf/ A) ,并对浸渗效果、复合材料的微观结构和力学性能进行了测试分析。结果表明硝酸铝溶液对 C纤维编织体有很好的渗透性 ,单丝纤维和纤维束之间被氧化铝基体均匀填充。实验制备的 Cf/ A复合材料密度为 1.94g/ cm3,开气孔率为 2 2 % ,室温抗弯强度为 12 1MPa,断裂应变达到 3%。     

复合材料液态浸渗挤压过程浸渗和传热行为的耦合分析

采用有限元法模拟液态浸渗挤压复合材料浸渗过程温度场,采用有限差分法模拟液态金属渗流场,将两者耦合分析计算,利用FORTRAN语言编程和ANSYS软件得到了浸渗区的温度变化曲线、浸渗前沿及浸渗速度随时间的变化等曲线。对模拟结果分析研究表明,纤维半径、浸渗压力、液态金属粘度系数和预制体体积分数等影响液态金属的浸渗速度及浸渗过程;选用合适的工艺参数,可以获得理想的浸渗区温度分布,从而为合理选择浸渗过程的工艺参数奠定了理论基础。     

多孔预制体对SiC/Al复合材料孔隙率的影响

采用无压浸渗法制备了SiC含量较高的SiC/Al复合材料,分析了造孔剂添加量对多孔预制体孔隙率的影响,利用铝液浸渗多孔体理论分析了多孔顸制体孔隙结构对复合材料孔隙率的影响.结果表明:通过添加造孔剂可以调节多孔预制体的孔隙结构,使预制体的孔隙率增加;多孔预制体的孔隙结构的变化可以调节复合材料的孔隙率.多孔预制体的孔隙率越高、孔隙尺寸越大,则铝液浸渗畅通,复合材料的孔隙率越小.     

高体积分数SiC_p/Al复合材料表面粉化的原因

在850℃下,分别用纯铝熔体或硅质量分数为5%,12.5%,20%的铝硅合金熔体浸渗反应烧结碳化硅(RBSiC)坯体,获得硅含量不同的高体积分数SiC_p/Al复合材料;该复合材料在空气中长时间放置后表面粉化,采用扫描电镜、X射线衍射仪、X射线能谱仪等分析了复合材料及其粉化后粉末的组织形貌及成分,并分析其粉化原因。结果表明:在空气中静置两个月后,硅含量低的复合材料(原料中硅质量分数为0,5%)表面形成大量粉末,硅含量高的复合材料表面则不会粉化,粉末主要为棒状和片状Al(OH)_3;复合材料制备过程中由于硅含量不足产生了碳化铝,碳化铝在空气中水解导致粉化。     

无压浸渗法制备SiCp／Al复合材料

对用无压浸渗法制备ＳｉＣｐ／Ａｌ复合材料的浸渗过程进行了分析。结果表明，通过对铝合金成分、制备工艺与浸渗深度关系的研究要可优化成分和工艺参数，并在研制过程中获得了验证。     

金属基复合材料液相浸渗工艺中孔洞缺陷

液相浸渗法是制造纤维增强金属基复合材料的先进工艺，本文根据热力学原理对金属液浸渗纤维空隙的过程进行了研究，发现纤维分布、纤维与液相基体的润湿性及外加压力是影响浸渗过程的主要因素，从而得到了控制液相浸渗过程，获得高质量复合材料的途径。     

铜基复合材料制备工艺的研究进展

高新科技的快速发展对高性能铜材料的开发提出了更高的要求,铜基复合材料因具有较高的强度和良好的导电导热性、耐磨耐腐蚀性、高温稳定性等而得到广泛的应用,其制备工艺在不断发展,且近年来取得了很大进展.综述了铜基复合材料主要制备工艺,包括粉末冶金法、铸造法、机械合金化法、内氧化法、原位合成法、熔体浸渗法和搅拌摩擦法等的特点及其研究进展,并对铜基复合材料制备工艺今后的发展方向进行了展望.     

自蔓延高温合成铝基复合材料研究

采用真空自蔓延高温合成和熔融金属渗入技术结合的工艺制备了致密的铝基复合材料。研究了预热温度对Ａｌ－Ｃｒ２Ｏ３燃烧体系绝热温度、燃烧速度以及最终铝基复合材料组织、性能的影响；同时就溶渗压力对铝基复合材料组织、性能的影响也作了研究。结果表明，随预热温度的升高（≤２００℃），材料组织均匀化，硬度、耐磨性提高；随熔渗压力的增加，铝基复合材料的性能优化；铝基复合材料的耐磨性远优于基体材料。     

Experimental studies and optimization of process parameters for burrs in dry drilling of stacked metal materials

In the drilling of stacked materials, burrs produced on both the surface layer and the interlayer have some undesirable characters with regard to assembly quality, and deburring is a time consuming and costly operation. This paper presented an experimental study on the dry drilling of Ti-6Al-4V titanium alloy and 7075-T6 aluminum alloy stacked materials, which was performed by using uncoated cemented carbide drills. The burr size was evaluated at various spindle speeds, feed rates, stacking sequences, and clamp forces. After which, the burr morphology was observed and analyzed. Finally, a new multi-objective optimization algorithm, which was derived from the game theory, was used to select optimum process parameters to minimize burr size. The best process parameters recorded in this paper were at the spindle speed of 2,000?r/min, the feed rate of 0.075?mm/r, the pressure of 0.3?MPa, and the stacking sequence of the Ti-6Al-4V titanium alloy on top of the 7075-T6 aluminum alloy.     

碳化硅颗粒增强铝基复合材料主要制备技术

随着严酷工程环境要求的不断提高,单一材料已无法满足现代工程应用的需求,具有高性能和新功能的先进复合材料尤其是金属基复合材料的需求日益增长。本文总结了近年关于碳化硅颗粒增强铝基复合材料的制备方法和性能特点,以便了解碳化硅颗粒增强铝基复合材料的主要制备技术及发展状况。     

Wear prevention in molds used to mold boron filled elastomers

An investigation was conducted to identify surface coatings which would improve the wear characteristics of compression molds used to mold contoured parts from elastomers filled with crystalline boron particles. An analysis was made of the mode of wear present on the surfaces of a production mold, followed by selection and modification of a capillary rheometer as the test device. Test specimens were coated by electroplating, electroless plating, plasma spraying, chemical vapor deposition, sputtering and a fused salt process. Testing was conducted under conditions simulating those encountered in the production molding operation.Techniques used in evaluating the results included optical microscopy, scanning electron microscopy, transmission electron microscopy and surface profilometry. The results are expressed as a ratio of volumetric wear of the tested coating to that of unprotected mold steel.Results indicate that titanium diboride (TiB₂) applied by chemical vapor deposition provides wear resistance superior to plasma sprayed aluminum oxide mixed with titanium dioxide, plasma sprayed chromium oxide, electrodeposited chromium, electroless nickel containing synthetic diamond powder, chemical vapor deposited tungsten carbide (W/W₂C), aluminum oxide and aluminum oxide over chromium carbide. Sputtered titanium diboride was also superior to these coatings and to sputtered titanium carbide and boron carbide.     

Planetary motion cross bar friction test for application in machining process

This paper describes a new method to evaluate the friction coefficient at the tool-work interface in machining process where high stress and temperature are caused. In order to examine the feasibility of the proposed method, the present report introduces the method and the results obtained only at room temperature. Ti6Al4V, SUS304, AISI1045, FCD 700, FCD 450 and FC300 were used as work materials, while TiN coated carbide tool, TiAlN coated carbide tool and P15 were used as tool materials. The proposed method provided the friction coefficients of different coatings against different work materials, and demonstrated the variability of friction coefficient and the anisotropy of surface roughness.     

一种远程多点监控装置的实现

该有毒/可燃性气体检测控制系统是一种基于PLC和触摸屏的新型测控设备.在系统中使用关键技术主要包括:在线监视、电磁阀联动箱的自动控制、可视化人机交互界面.文中描述了这些系统结构与设计过程.     

碳化硅颗粒增强铝基复合材料的制备及应用的研究

综述了碳化硅颗粒增强铝基复合材料（SiCp/Al基复合材料）的研究进展,重点阐述了国内外现阶段碳化硅颗粒增强铝基复合材料的常用制备方法,并结合其应用现状进一步分析了各种常用制备方法的优缺点和未来的研究方向,在此基础上展望了其未来的发展和应用前景。     

On-machine tool resharpening process for dry machining of aluminum alloys employing LME phenomenon

Dry machining of aluminum alloys is known to be one of the most difficult metal cutting operations. The issues involved are that without use of cutting fluids, these materials severely adhere to the tool surface and form a built-up edge due to their low melting point and high ductility, leading to deterioration of the surface integrity of the workpiece and tool failure. To overcome this problem, the present study proposes a novel strategy for removing the adhesion layer from the tool surface and recovering the cutting tool performance without detaching the cutting tool from the machine tool, namely, an on-machine tool resharpening process. To achieve efficient removal of the aluminum adhesion layer from the tool surface, the phenomenon of liquid metal embrittlement (LME), which is defined as a brittle fracture, or loss in ductility, of a ductile material in the presence of a liquid metal is employed. A series of experiments using a WC-Co cemented carbide tool and liquid gallium showed that the newly developed strategy employing LME is highly effective in removing the adhesion layer without damage to the tool substrate and has great potential for addressing the issues related to the dry machining of aluminum alloys.     

CVD金刚石涂层拉拔模的制备

针对拉制铝管用尼龙模具寿命短和硬质合金模具粘铝的问题,采用微波等离子体CVD法在硬质合金拉拔模内孔壁涂覆金刚石薄膜。通过设计一个特殊支撑结构,引导等离子体进入拉拔模内孔,可实现在内孔8mm深度范围一次沉积出金刚石膜。现场拉拔试验表明,金刚石涂层模拉制的铝管光洁度介于尼龙模和硬质合金模之间,可满足使用要求。     

CVD金刚石厚膜刀具切削性能的试验研究

分析了CVD金刚石厚膜刀具材料的性能特点 ,对CVD金刚石厚膜车刀进行了精密切削和难加工复合材料切削试验 ,结果表明 :CVD金刚石厚膜刀具加工铝合金的表面粗糙度可达Ra0 0 5 μm ;切削难加工复合材料时刀具耐磨性和使用寿命明显优于硬质合金刀具、PCBN刀具和PCD刀具     

Dry wear and friction properties of an A356/SiC foam interpenetrating phase composite

The dry sliding wear and friction behaviors of A356 aluminum alloy and a hybrid composite of A356 aluminum alloy and silicon carbide foam in the form of an interpenetrating phase composite were evaluated using a ball-on-disk apparatus at ambient conditions. The stationary 6.35 mm alumina ball produced a wear track (scar) diameter of 7 mm on the rotating specimen surface. Three different loads; 5 N, 10 N and 20 N were applied at a constant sliding speed of 33 mm/s for both materials. Wear tracks were characterized with a scanning electron microscope and measured with an optical surface profilometer. In general, this novel A356/SiC foam composite reduced the friction coefficient and wear rate from that of the base alloy for all loading conditions. In addition, as the load increased, the friction coefficient and wear rate decreased for both materials. The results indicate the composite could be used in light-weight applications where moderate strength and wear properties are needed.