简介:通过热压烧结工艺制得了(SiCp+C)/MoSi2复合材料,测试分析了材料的组织结构、室温和高温力学性能.结果表明:(SiCp+C)/MoSi2复合材料主要由MoSi2(大量),α-SiCp(大量),Mo5Si3(多量)和β-SiC(少量)组成,密度为5.12g/cm3,相对密度为91%;增强相的粒径<30μm,体积分数为39%.其室温硬度、抗弯强度和断裂韧性分别为12.2GPa,530MPa和7.2MPa·m1/2;材料在800℃的维氏硬度为8.0GPa,1200和1400℃的抗压强度分别为560MPa和160MPa.与非增强MoSi2相比,材料的各种力学性能都有大幅度的提高.
简介:在劳动争议处理活动中,及时、准确地确定企业当事人资格,是劳动争议处理机构依法处理劳动争议的重要前提.但由于现行劳动法规对此没有做出明确的界定,在劳动仲裁工作实践中仲裁机关及其工作人员至今仍被种种不同的选择标准所困扰,致使一些争议案件得不到及时的受理和调处.其中比较常见的选择标准一是以法人资格为标准,即企业必须具备法人资格才可以充当企业当事人;二是以招工权为标准,即由具有招工权和人事管理权的企业主管部门来充当企业当事人.笔者认为,之所以出现这种现象,与我国传统的劳动法研究与教学不无关系.本文拟对此作一粗浅分析.
简介:C/C复合材料在高于450℃的空气(氧化气氛)中会显著氧化,可采用基体抗氧化和涂层抗氧化来防止其氧化.作者采用在基体材料表面预先浸涂浸渍剂,再涂刷涂层并将涂层固化处理制备涂层的工艺方法,制备出抗氧化性能良好的抗氧化涂层.预浸涂处理可使材料的起始氧化温度提高近200℃.单独预浸涂以硼酸、TEOS为主的浸渍剂抗氧化效果不明显,而预浸涂以磷酸+硼酸混合液、磷酸为主的浸渍剂效果较好.其最佳抗氧化效果为900℃×2h静态氧化失重率为0.33%,900℃×4h静态氧化失重率为1.13%.对以硼酸、磷酸和TEOS及其混合液为主的浸渍剂的抗氧化机理进行了探讨.
简介:TheinfluenceofrareearthoxideCeO2onmicrostructureandwearresistanceofM80S20thermalsprayandthermalsprayweldingcoatingsisstudiedusingopticalmicroscope,scanningelectronmicroscope,X-rayenergydispersionspectroscope,X-raydiffractometerandweartestingmachine.Theresultsshowthattheaddi-tionof8%CeO2canimprovethemicrostructure,microhardnessandwearresistanceofcoatingssignificantly.
简介:RE-dopedNi-basedcatalystswerepreparedbysol-gelmethod.ThesecatalystswereappliedtothereactionofCO2reformingCH4tosyngas.ThestudiesrevealthatRE-doped(RE=La,Ce,Sm,Yb)Ni-basedcatalystsshowhighercatalyticactivitythanundopedNi-basedcatalyst,andwiththeincreasingofRE-dopedquantity,thecatalyticactivityofcatalystsexhibitsregularchanges.WhenRE-dopedquantityis0.2%(molarratio),thecatalystsshowthebestcatalyticactivity.
简介:TheNd60Fe20Al8Co10B2alloywaspreparedbysuctioncastingofthemoltenalloyintoacoppermoldunderargonatmosphere.Themicro-structuralandmagneticpropertychangesintheNd60Fe20Al8Co10B2alloyduringcrystallizationwereinvestigatedbyX-raydiffraction(XRD),differentialscanningcalorimetry(DSC),scanningelectronmicroscope(SEM)andthevibratingsamplemagnetometer(VSM).TheprecipitationandNd-richandFe-richphaseshavenosignificanteffectontheintrinsiccoercitityforNd60Fe20Al8Co10B2alloyannealedbelow723K.However,thegrowthofFe-richphasedecreasesthesaturatemagnetizationandremanenceofthealloy.Thehardmagneticbehaviorisdisappearedwhenthealloyisfullycrystallized.