Al_2O_3/TiB_2/SiC_w陶瓷材料的室温摩擦磨损特性研究

研究了不同SiCw，含量的Al2O3／TiaO／SiCw，陶瓷材料与硬质含金在室温滑动摩擦时的摩擦磨损特性．结果表明：随SiCw含量的增加摩拣系数减小，Al2O3／TiB2／SiCw陶瓷材料抗磨损能力增强，其磨损机制主要有后粒磨损和晶须的脱落，晶须的取向对该陶瓷材料的耐磨性能有很大的影响。     

A12O3／SiCw陶瓷材料中晶须的极限和最佳含量探讨

从Ａ１２Ｏ３与ＳｉＣ晶须热胀失配分析入手，分析了Ａ１２Ｏ３／ＳｉＣｗ。陶瓷材料中晶须的极限含量，得出了晶须的极限含量为４３ｖｏｌ％。研究表明：晶须含量超过极限值时，Ａ１２Ｏ３／ＳｉＣｗ强度大幅下降的主要原因有二个，即１．材料的致密度急剧降低，气孔率增大；２．由于热胀失配所产生的残余张应力导致基体材料的开裂。通过实验证明，当晶须含量为２０￣３０ｖｏｌ％时，Ａ１２Ｏ３／ＳｉＣｗ。陶瓷材料能获得最佳增韧     

热胀失配对Al_2O_3/TiB_2陶瓷材料高温断裂韧性的影响

研究了由于热胀失配所产生的残余应力对Al2O3／TiB2陶瓷复合材料的高温断裂韧性KIC的影响。结果表明：Al2O3／TiB2陶瓷材料的KIC随温度的升高而略有增加，其主要原因是由于基体材料中的残余拉应力随温度的升高而松驰，经热胀失配分析计算得到材料的高温KIC的增幅与实际测量的结果具有很好的一致性，通过对该材料的热胀失配分析，可以预测其KIC随温度的变化规律。     

TiB_2和SiC_w对Al_2O_3陶瓷材料力学性能及微观结构的影响

以TiB2颗粒和SiC晶须对Al2O3陶瓷进行增韧补强,采用热压法同时了制备了Al2O3,Al2O3／TiB2和Al2O3／TiB2／SiCw三种陶瓷材料,研究了TiB2颗粒和SiC晶须对Al2O3陶瓷材料的力学性能和微观结构的影响。结果表明;因TiB2的加入可明显改善Al2O3。陶瓷材料的强度、硬度和韧性;而TiB2颗粒和SiC晶项协同对Al2O3进行增韧补强可使其断裂韧性显著提高。Al2O3／TiB2陶瓷材料的主要增韧机理有;TiB2粒子的针扎作用和使裂纹产生偏转;而Al2O3／TiB2／SiCw陶瓷材料的主要增韧机理有：晶须拔出、裂纹桥接和裂纹偏转。     

Al_2O_3-(Ti,W)C-SiC_W陶瓷材料的工艺性能

研究了Al2O3－（Ti，W）C—SiCw陶瓷材料的工艺性能．进行了晶须含量、热压温度、时间及热压压力四因素三水平L9（34）正交实验．分析了这些因素对复合材料的致密度、硬度、抗弯强度及断裂韧性的影响，从中获得了抗弯强度及断裂韧性最佳时的工艺参数。     

氧化铝基复合陶瓷-金属钎焊界面的热应力

用Ag-Cu-Ti钎料钎焊SiCw／Al2O3复合陶瓷和金属时，陶瓷与钎料发生化学反应，在陶瓷表面形成由TiO、TiC等物相组成的反应层。采用有限元法，对SiCw／Al2O3复合陶瓷／反应层界面的热应力进行了计算。结果表明，复合陶瓷／反应层界面的残余应力变化急剧，最大拉应力位于晶须、基体和反应层交界处；晶须内部及其表面存在较高的双向压应力，Al2O3基体主要承受垂直于界面的拉应力；SiC晶须／反应层界面及其附近的反应产物TiC内具有较高的平行于界面的拉应力，当连接界面承受剪力作用时，SiC晶须／反应层界面和TiC处极易破坏。借助TEM和SEM观察了复合陶瓷／反应层界面区的精细结构和剪切断口形貌，并利用计算结果对观察到的现象进行了分析。     

TiB_2/SiC_w陶瓷复合材料的研究

采用热压工艺制备了TiB_2／SiC_w陶瓷复合材料。在TiB_2基体中添加适量的SiC_w晶须，可显著的提高材料的断裂韧性和抗弯强度。采用有限元法计算了由于基体和晶须熟膨胀系数失配所产生的残余应力及其分布，分析热胀失配所产生的残余应力对材料增韧特性的影响。结果表明：晶须径向及轴向均受残余压应力的作用；晶须拔出和桥联为该复合材料的主要增韧机制。     

Fe3Al/ZrO2复合材料海水腐蚀电化学行为

用电化学阻抗、极化曲线、扫描电镜等测试手段研究单相Fe3Al和Fe3Al／ZrO2复合材料的耐海水腐蚀性能。结果表明：浸蚀初期，材料的抗局部腐蚀能力由强到弱依次为单相Fe3Al〉Fe3Al（75 vol％）／ZrO2〉Fe3Al（50 vol％）／ZrO2，但随着浸蚀时间的延长，Fe3Al（50 vol％）／ZrO2复合材料的腐蚀速率下降较快；浸蚀30d后，其抗海水腐蚀性最好。     

添加剂对氧化锆陶瓷抗热震性能的影响

对氧化锆陶瓷材料的抗热震性能进行了研究，探讨了A12O3添加剂的含量对氧化锆陶瓷材料的抗热震性能的影响。添加不同含量Al2O3添加剂时，氧化锆陶瓷材料的抗热震性能也随之变化，通过研究发现，添加10％Al2O3（质量分数，下同）时，氧化锆陶瓷材料的抗热震性能最好。运用XRD、SEM等手段对氧化锆陶瓷材料进行物相、微观结构方面的分析，并以此为基础对氧化锆陶瓷材料抗热震性能的影响因素进行了探讨。     

Y-Ce-TZP／Al2O3复相陶瓷空气环境下退火的相变行为

研究了不同烧结温度和不同Al2O3含量的Y-Ce-TZP／Al2O3复相陶瓷在300℃空气环境下退火的相变行为，并考察了复相陶瓷的力学性能，对相变发生进行了热力学分析。结果表明：Al2O3抑制了退火过程氧化锆t→m相变，当Al2O3含量为15％（质量分数，下同），烧结温度为1450℃时Y-Ce-TZP／Al2O3复相陶瓷退火前的抗弯强度与断裂韧性分别为743MPa和10．0MPa．m^1/2退火10d后仍达到731MPa和9．9MPa．m^1/2。     

时效对SiCw/2024Al复合材料应力腐蚀开裂行为的影响

采用双悬臂梁试验方法研究了经时效处理的SiCw／2024Al复合材料在3．5％NaCl溶液中的应力腐蚀行为，用透射电子显微镜对时效处理后复合材料的微观组织形貌进行了观察与分析，用扫描电子显微镜观察应力腐蚀试样的裂纹扩展形貌．结果表明，在3种不同的时效状态下，复合材料内部的微观组织形貌发生了较大的变化，引起3种时效状态下复合材料的应力腐蚀行为发生变化，相应的裂纹尖端的微观组织形貌也出现了较大的差别．     

SiC晶须增强6061Al基复合材料的热机械疲劳性能 Ⅰ．应力应变行为

对体积分数为15%和28%的SiCW/6061Al复合材料进行了同相和反相热机械疲劳（TMF）实验,研究了疲劳过程中的应力应变行为和变形机制。结果表明,两种材料在同相和反相加载下均表现为循环软化;反相加载产生拉伸平均应力,同相加载产生压缩平均应力;在相同应变范围下,高体积分数复合材料的循环应力范围比低体积分数复合材料的应力范围大。     

Thermal Relaxation of Residual Stresses in Shot Peened Surface Layer of SiCw/Al Composite

The residual stress relaxation of the shot peened layer on the SiCw/Al composite during isothermal annealing was investigated. The results showed that the residual stresses relaxed in the whole deformation layer especially when the annealing temperature was higher than 200?°C. The relaxation process during isothermal annealing could be described precisely using Zener-Wert-Avrami function. Because of high intensity dislocation around reinforcements producing a large amount of stored energy, the residual stress relaxation activation enthalpy of shot peened SiCw/Al was smaller than self-diffusion activation enthalpy of pure aluminum. According to the analysis of full-width at half-maximum (FWHM) of the shot peened composite in different annealing temperatures, it can be concluded the recovery and recrystallization behavior became intensely when anneal temperature was larger than 200?°C. The small relaxation of residual stress in low annealing temperature was mainly due to partly recovery and recrystallization in a very low level.     

Diffusion welding process and joint''''s microstructure behavior of SiC_w/6061Al composite

The rules such as process parameters affecting joint properties and the evolution principle of weld's microstructure have been researched by adopting diffusion welding process to connect SiCw/6061Al composite. Experimental results show that there exists a critical temperature region between solid and liquid phase line of SiCw/6061 Al composite, and the region will shrink with the increasing of welding pressure. When diffusion welding occurred under the critical temperature region, welding joint exhibits bad property of bonding, and the matrix and the reinforcement can't bond effectively. When diffusion welding occurred in the critical temperature region, the strength of welding joint changes widely with the variation of welding temperature. When welding temperature varies in 10癈, the strength of welding joint will change obviously. Only when welding temperature is higher than the critical temperature region, stable joint properties can be obtained. Simultaneously the matrix and the reinforcement has bet     

凝胶注模成型工艺制备SiCw/Al2O3陶瓷复合材料的性能研究

对SiC2/Al2O3陶瓷的低粘度、高固相体积分数浓悬浮体的制备以及凝胶注模成型后坯体的性能和显微结构进行了研究,着重分析了长径比不同的2种SiC晶须及其添加量对坯体性能的影响.结果表明,坯体的相对密度、抗弯强度与SiC晶须的长径比和添加量有关,浆料的粘度随着晶须长径比和添加量的增大而增加.坯体的抗弯强度随着晶须添加量的增加呈现一种先上升后下降的趋势.凝胶注模成型后坯体结构均匀、致密,相对密度为60%,抗弯曲强度达38.5 MPa.通过显微结构观察,裂纹偏转、晶须拔出和晶须桥连是晶须增强的主要机制.     

纯铝基复合材料的应力腐蚀与氢致开裂

采用双悬臂梁（DCB）恒位移试验方法，Ⅱ型恒载荷试验方法以及慢为速率拉伸（SSRT）试验方法对纯Al复合材料的应力腐蚀与氢致开裂行为进行了研究，结果表明，在不发生应力腐蚀与氢致开裂的纯铝中加入20％（体积分数，下同）的SiC晶须或Al18O33晶须后就会发生应力腐蚀及氢致开裂。     

SiCw／Al复合材料X射线衰减系数及缺陷检测灵敏度

研究２０％Ｖ／Ｖ ＳｉＣｗ／６０６１Ａｌ复合材料的Ｘ射线衰减系数及缺陷检测灵敏度（相对值）,对管电压较低时,复合材料的Ｘ射线衰减系数较大,且缺陷检测灵敏度较差：当管电压〉１００ｋＶ时,两种材料的Ｘ射线衰减系数及缺陷检测灵敏度差别很小。     

Load transfer mechanism and mechanical properties of SiCw/Al metal matrix composites

The load transfer mechanism and mechanical properties of SiC whisker reinforced aluminum matrix composites were investigated. A generalized shear-lag model was proposed to analyze the effects of the aspect ratio, misorientation angle and volume fraction of SiC whisker on the mechanical properties of SiCw/Al composites. A new concept on effective aspect ratio was suggested, combining the effects of aspect ratio and alignment of whiskers, to calculate the effective stress acting on the aluminum matrix in SiCw/Al composites. The magnitude and anisotropy of the yield strength of the SiCw/2124Al composite can be estimated more accurately by substituting the average aspect ratio with the effective aspect ratio based on the generalized shear-lag model. The SiCw/2124Al composite with the largest effective aspect ratio showed the lowest minimum creep rate which decreased with increasing effective aspect ratio of SiC whisker, but were found to be almost similar under the same effective stress acting on the Al matrix. It is suggested that the role of SiC whisker is to improve the mechanical properties by reducing the effective stress acting on the Al matrix in the SiCw/Al metal matrix composite. This article is based on a presentation made in the symposium “The 1^st KIM-JIM Joint Symposium: High Strength Ratio Aluminum Alloys”, held at Inha University, Inchon, Korea, October 22. 1999 under the auspices of The Korean Institute of Metals and Materials and The Japanese Institute of Metals.     

EFFECTS OF DIFFUSION WELDING PARAMETERS ON JOINT STRENGTH OF SiCw/6061AI COMPOSITE

1.IntroductionInthispaper,diffusionweldingwajsusedtoweldSiCw/6061AIcomposites.Effectsofprocessingparameterssuchassurfaceconditionofweldingspecimen,pressuregandweldingtemperatureonjointstrengthandmicrostructureintheweldwerestudied,andappropriateweldingmethodologywajsidentified.Thepaperwasilltendedtoprovidetheexperimelltaldataandtheoreticalbasisforthepracticalapplicationofthiskindofcomposites.2.ExperimentalSiCw/6061AIcompositewasfabricatedbymeansofsqueezecasting.Itstensilestrengthis280MPa.D…