激光表面熔凝处理对30Cr2Ni4MoV转子钢高温水腐蚀性能的影响

进行了三种强度级别的30Cr2Ni4MoV钢的激光表面熔凝处理,用电化学极化曲线和高温应力腐蚀试验考察了其耐腐蚀性能。研究表明:激光熔凝处理后在30Cr2Ni4MoV表面形成了约10~20μm的致密马氏体硬化层和压应力状态,基材状态对激光熔凝硬化层的性能无明显影响,但激光功率增大会导致表面熔凝层硬度水平降低;激光表面熔凝处理使腐蚀电位左移,腐蚀电流密度减小,抗腐蚀性能明显增强。     

新旧混凝土界面结合状态研究

研究了在不同的界面干湿状态下，几种常见的修补材料和界面剂对新旧混凝土界面结合强度的影响。运用拉拔强度评价新旧混凝土界面结合状态，并借助显微硬度仪测量界面处的显微硬度值对试验结果进行了验证和分析。结果表明，在界面处于不同的干湿状态时，提高新混凝土的强度可使结合强度略有增大。在修补材料中掺入纤维会明显提高界面结合强度，且聚丙烯纤维要优于碳纤维．使用界面剂后界面干湿程度对界面结合强度影响减小。     

电沉积软磁铁箔性能的研究

为优化电沉积制备软磁铁箔的工艺条件,研究电解液温度和阴极电流密度对铁箔的磁学、力学和电学性能的影响规律,采用软磁材料测试仪、直流电阻电桥和显微硬度计研究了工艺条件变化时对铁箔的磁参数、电阻率和显微硬度的影响,并对铁箔的金相显微组织进行分析.结果表明:阴极电流密度增大时,铁箔的矫顽力增大,最大磁导率降低,显微硬度值及电阻率均提高;电解液温度提高时,铁箔的矫顽力降低,最大磁导率增大,显微硬度值下降,而电阻率提高;在650℃经过真空退火后的铁箔矫顽力降低,最大磁导率提高,其电阻率和硬度都下降,韧性明显提高.电沉积工艺条件改变时,薄膜的晶粒尺寸影响铁箔性能的变化.     

CBN-WC复合片烧结的研究

进行了高温高压合成多晶立方氮化硼(PCBN)复合片的研究,实验采用二次烧结法,即直接用CBN粉末在WC-Co基底上进行烧结。烧结压力为5.5GPa,烧结温度为1200℃至1700℃,烧结时间3分钟。实验结果表明,在1200℃至1500℃的范围内,烧结体的硬度随着烧结温度的升高而显著增加,实验在1500℃的烧结温度下得到了Knoop硬度36.7GPa的CBN烧结体(PCBN),而在1500℃至1700℃的范围内,烧结体的硬度无明显变化。     

钨靶件试样的热等静压工艺试验研究

分别选用锆和不锈钢作为ADS固体W靶的包壳材料，采用真空电子束焊制备了W-Zr及W-S.S.的小样品，在1200、1300、1400℃和180MPa下研究它们的热等静压（HIP）工艺条件。对HIP后的试样分别进行结合面微观观察、扩散层厚度，成分及其显微硬度的测试分析。结果表明：钨-锆及钨-不锈钢包壳管均结合紧密良好，未见间隙或微裂纹,也未见钨的晶粒长大；在钨-锆包壳管结合面处主要是锆向钨扩散，而钨向锆扩散很少。在本试验条件下，其扩散层深度在6-9µm；钨-不锈钢包壳管结合面处钨和铁的扩散明显，其扩散层深度约为13μm，而铬和镍的扩散较少；W-Zr及W-S.S.结合面的显微硬度值也表明在钨-锆及钨-不锈钢的结合面上有扩散层存在；在1300℃，180MPa进行等静压后，不锈钢包壳管的部分区域熔化，因此，1200℃，180MPa适合于钨-不锈钢，而1300℃，180Mpa最适合于钨-锆。     

Research on the inwall shot blasting of the S30432 high-pressure boiler tube

Inwall shot blasting is a method of improving the surface hardness and high temperature oxidation resistance of the S30432 high-pressure boiler tube.The differences on residual stress,sub-grain size,micro-hardness and structure between the S30432 inwall shot-blasting tube produced by Baosteel with six technological process parameters and the imported super 304H were studied systematically by contrast test research.It has been demonstrated that the S30432 obtains a higher residual stress,a deeper distributed layer and a better sub-grain size of the inwall field shot-blasting layer;the martensite content of the shot-blasting surface was low;and micro-hardness and structure refinement were better.After 2000 h' oxidation test under the 650℃/26MPa steam condition,steam oxidation resistance of the Baosteel steel tube shot-blasting surface was higher,the oxide layer was thinner,and was well combined with bulk material.     

硼铸铁缸套QPQ盐浴复合处理的组织和性能研究

利用扫描电子显微镜(SEM)分析了硼铸铁缸套QPQ(淬火-抛光-淬火)处理后的表面形貌、氮化层深度;采用401MVA型显微维氏硬度计测量试样显微硬度;在M-2000型磨损试验机上进行滑动磨损试验;采用10%NaCl水溶液浸泡法对其进行抗蚀性测试。研究结果表明:硼铸铁经QPQ盐浴复合处理后,得到了一定厚度的白亮层和扩散层,使金属零部件表面形成高硬度、高耐磨性能的氮化物层,组织和性能稳定,表层显微硬度最高达到1010HV0.1,是基体显微硬度的3倍以上。耐磨性和抗腐蚀性较渗氮前都有大幅度提高。并用该工艺方法对硼铸铁缸套进行了批量生产,实际应用表明可使硼铸铁缸套使用寿命大大提高,易于推广应用。     

H80薄板拉伸性能的尺寸效应

为了研究薄板拉伸性能的尺寸效应及其产生的微观机制,对晶粒尺寸相似但厚度不同的H80薄板试样进行了拉伸试验和显微硬度试验.通过建立晶界区域强化模型和晶粒间的弱弱组合变形机制,研究了薄板的厚度尺寸、晶粒尺寸及显微硬度分布对拉伸力学性能的影响.结果显示:强度指标值和塑性指标值均随厚度尺寸的减小而降低,呈现越小越弱的尺寸效应现象,但强度指标和塑性指标的变异因子值却呈现越小越强的相反规律.薄板的横向硬度均值随厚度尺寸的增大而增大,而横向硬度值的变异因子却随厚度尺寸的增大而减小.随厚度尺寸的减少,晶界区域所占百分比的减少和单个晶粒所占百分比的增加是产生拉伸性能尺寸效应现象的根本原因.此外,显微硬度分析表明:易变形区域形成的概率随厚度尺寸的减小而增大,易变形区域的集中变形是引起薄板试样过早断裂的原因.     

硬化工艺对双辉渗银不锈钢膜层结构及性能的影响

不锈钢双辉渗银处理获得的渗银层硬度较低且不耐磨,因此设计硬化方案对渗银不锈钢进行硬化,以改善其耐磨性。采用等离子氮碳共渗技术进行渗银层的改性工作,对不同工艺下膜层的微观形貌、成分及物相构成进行了分析,并对比了其硬度及磨损性能。两种硬化工艺下测得的硬度及磨损试验数据如下:渗银处理(×3h)+渗氮碳处理(×10h)工艺制备的试样表面硬度值为283HV0.025,15s,平均摩擦系数为0.4287,磨损失重为12.9mg;渗氮碳处理(×10h)+渗银处理(×3h)工艺制备的硬度值为544HV0.025,15s,平均摩擦系数为0.4266,磨损失重为11.5mg。可以看出渗银处理(×3h)+渗氮碳处理(×10h)工艺未提升渗银不锈钢的表面硬度,渗氮碳处理(×10h)+渗银处理(×3h)工艺将渗银不锈钢的表面硬度提升了近1倍。两种硬化工艺对渗银不锈钢的耐磨性能略有改善。     

Effect of TiO2 additions on densification and mechanical properties of new mulltifunction resistant porcelains using economic raw materials

The aim of this work is to determine the effect of TiO₂ on sintering and mechanical proprieties of new multifunction resistant (MFR) porcelain prepared from local abundant raw materials. Based on a preliminary work, the new selected composition was 30 wt% kaolins (20 wt% kaolin halloysite type + 10 wt% kaolin Tamazart), 45 wt% k-feldspar and 25 wt% quartz and containing different contents of TiO₂ (3, 5 and 8 wt%). The sintering temperatures of mixtures were between 1140 and 1260 °C. Subsequently, the obtained phases in the elaborated samples were investigated by X-ray diffraction and Fourier transform infrared spectroscopy analyses, Raman spectroscopy and SEM analysis. The optimum sintering conditions gave a higher bulk density (2.47 g.cm⁻³) and excellent mechanical properties: The three point flexural strength (3PFS), Vickers micro-hardness (VMH) and apparent porosity (P_A) of porcelains sintered at 1160 °C were 238 MPa, 12.3 GPa and 2%, respectively. This obtained 3PFS value is drastically higher than that achieved for conventional porcelains (ranged between 60 and 80 MPa). Moreover, these two best 3PFS (238 MPa) and VMH (12.3 GPa) values achieved for this new MFR porcelains were considerably higher when compared to those values (3PFS=218 MPa and VMH=6.5 GPa) obtained by others for porcelain −30% ZrO₂ composite, even though their mixtures were hot pressed in vacuum at 970 °C for 2 min. Besides, the maximum value achieved for the new MFR porcelains is nearby that of the flexural strength of porcelain containing 5 wt% TiO₂ and 30 wt % alumina (about 240 MPa). In other words, the presence of 30 wt % alumina in their product well confirm the benefic effect of the used raw materials (saving 30 wt % alumina) on porcelain strengthening.