硬度对碳钢微动磨损行为和磨屑组分的影响

人们已经研究过诸多因素对金属和合金微动磨损行为的影响，但对试样硬度与磨屑组分、微动磨损表面形貌及压实氧化物层的形成之间的关系却还很少有人研究。因此，利用ＳＤＶ微动磨损试验机在室温下于大气中就硬度对４５＾＃钢微动磨损行为和磨屑组分的影响进行了考察。     

激光淬火和冲击复合强化处理40Cr钢的耐磨性能研究

对激光淬火40Cr钢强化区域进行激光冲击复合强化处理，并分别同激光淬火和氮化处理40Cr钢对比考察了激光淬火和冲击复合强化处理40Cr钢的表面硬度和耐磨性．结果表明：经激光淬火和冲击复合强化处理的40Cr钢的硬度比激光淬火处理40Cr钢的硬度高11％；同氮化和激光淬火处理40Cr钢相比，复合强化处理40Cr钢的耐磨性分别提高了约4．3倍和1．6倍．     

化学镀Ni-P-PTFE镀层的摩擦学性能研究

本文以CuSO_4作为镀液稳定剂、氟碳表面活性剂作为分散剂制备了Ni-P-PTFE复合镀层,并且考察了热处理温度对镀层的摩擦磨损行为、硬度、相组成和微结构的影响。结果表明,200℃热处理对镀层的硬度、微结构及耐磨性都没有明显的影响,300—400℃热处理之镀层的硬度和耐磨性均明显提高,当热处理温度为360℃时,镀层产生明显的晶化,400℃热处理的镀层具有最高硬度、最低摩擦系数和最佳耐磨性。     

Pressure-induced structural transition and thermodynamic properties of RhN2 and the effect of metallic bonding on its hardness

The elastic constant, structural phase transition, and effect of metallic bonding on the hardness of RhN2 under high pressure are investigated through the first-principles calculation by means of the pseudopotential plane-wave method. Three structures are chosen to investigate for RhN2, namely, simple hexagonal P6/mmm （denoted as SH）, orthorhombic Pnnm （marcasite）, and simple tetragonal P4/mbm （denoted as ST）. Our calculations show that the SH phase is energetically more stable than the other two phases at zero pressure. On the basis of the third-order Birch Murnaghan equation of states, we find that the phase transition pressures from an SH to a marcasite structure and from a marcasite to an ST structure are 1.09 GPa and 354.57 GPa, respectively. Elastic constants, formation enthalpies, shear modulus, Young＇s modulus, and Debye temperature of RhN2 are derived. The calculated values are, generally speaking, in good agreement with the previous theoretical results. Meanwhile, it is found that the pressure has an important influence on physical properties. Moreover, the effect of metallic bonding on the hardness of RhN2 is investigated. This is a quantitative investigation on the structural properties of RhN2, and it still awaits experimental confirmation.     

Theoretical investigation on the electronic structure,elastic properties, and intrinsic hardness of Si2N20

According to the density functional theory we systematically study the electronic structure, the mechanical prop- erties and the intrinsic hardness of Si2N2O polymorphs using the first-principles method. The elastic constants of four Si2N2O structures are obtained using the stress-strain method. The mechanical moduli （bulk modulus, Young’s mod-ulus, and shear modulus） are evaluated using the Voigt-Reuss-Hill approach. It is found that the tetragonal Si2N2O exhibits a larger mechanical modulus than the other phases. Some empirical methods are used to calculate the Vickers hardnesses of the Si2N2O structures. We further estimate the Vickers hardnesses of the four Si2N2O crystal structures, suggesting all Si2N2O phases are not the superhard compounds. The results imply that the tetragonal Si2N2O is the hardest phase. The hardness of tetragonal Si2N2O is 31.52 GPa which is close to values of β-Si3N4 and γ-Si3N4.     

晶体中的各向异性研究

晶体在生长和使用过程中均表现出其独特的各向异性。本文针对一些典型的无机材料在结晶生长和机械性能方面的各向异性,构建了组成与性质之间的关联关系,确立了从材料的组成出发定量计算和预测其物理化学性质的模型方法。结晶生长的化学键合理论揭示了材料的各向异性生长形态取决于微观层次上不同结晶方向的表面键合结构,材料硬度的电负性模型揭示了组成原子的电负性和键合方式决定了材料硬度的各向异性。     

络黑T光度法测定水的硬度

目前 ,水的硬度测定方法有 EDTA络合滴定法 [1]、偶氮氯膦 光度法 [2 ]及 4-甲基偶氮胂 光度法 [3] ,而络黑 T光度法则未见有文献报道。试验发现 ,在一定条件下 ,络黑 T与钙、镁形成的络合物具有相同的最大吸收波长 ,灵敏度基本一致。由此建立了一种测定钙、镁总量的新方法。该方法简便、快速。用于自来水和锅炉水的硬度测定 ,结果满意。1　试验部分1 .1　主要试剂与仪器钙标准溶液 :称取基准碳酸钙 0 .1 0 0 0 g于烧杯中 ,加少许水 ,滴加盐酸 (1 1 )使其溶解 ,煮沸 ,冷却后定容至 1 L,使用时稀释成 4.0μg· ml-1标准溶液。镁标准溶…     

可控硬度多层膜对肿瘤细胞行为的影响

以层状组装多层膜为基础,利用电化学方法精确可控的特点,构建了具有不同硬度的多层膜,并研究了该材料体系对细胞行为的影响规律.采用恒电流法,将聚吡咯(PPy)均匀复合进入聚赖氨酸/透明质酸(PLL/HA)多层膜内部,通过控制通电时间得到不同交联度的(PLL/HA)n@PPy多层膜.利用纳米压痕技术测试了多层膜在交联前后的硬度变化,并进一步研究了该多层膜体系对肿瘤细胞的黏附、增殖和迁移行为的影响.     

慢性舒张性心力衰竭患者动脉僵硬度影响因素分析

目的探讨慢性舒张性心力衰竭患者动脉僵硬度的影响因素.方法选取慢性舒张性心力衰竭患者354例,测量身高、体重、血压,计算BMI,采集空腹静脉血分析血脂、血糖、血浆B型脑钠肽(BNP)等指标,超声心动图检查各项指标,采用动脉硬化检测仪测量CAVI,分析CAVI与各临床特征的相关性.结果单因素相关分析结果显示,CAVI与年龄、收缩压、BNP呈明显正相关(r=0.3664、0.1193、0.2591,P<0.05或0.01),与BMI、E/A呈显著负相关(r=0.2040、0.1759,均P<0.01);多元逐步回归分析显示,高龄、女性、吸烟史、BMI、BNP、E/A是CAVI的独立影响因素(β=0.0443、0.2617、-0.0675、0.3904、0.4939、-0.7899,P<0.05或0.01),且E/A比值作用最强(P<0.05).结论老龄、女性、吸烟、BMI、BNP、E/A是影响慢性舒张性心力衰竭患者动脉僵硬度的主要危险因素.