填充系数和异氰酸酯指数对聚氨酯硬泡力学性能影响的研究

研究了填充系数、异氰酸酯指数和模具温度对恒定密度为350 kg/m3全水发泡硬质聚氨酯泡沫力学性能的影响。结果表明,压缩强度随各变量数值的增加均呈现上升的趋势,而弯曲强度表现出了不同的变化趋势。填充系数由2.0增大到3.0时,平均泡孔直径由188μm减小为151μm。     

碳化硅复合陶瓷耐磨性能研究

研究了常压烧结碳化硅复合陶瓷的耐磨性能及碳化硅复合陶瓷减摩性能、摩擦副优化配对等。研究结果表明,高速高压摩擦磨损试验中,碳化硅复合陶瓷与不同摩擦副材料配对,摩擦系数均小于0.2。     

几种火焰喷焊自熔性合金层的耐磨性能

研究了不同自熔性合金粉末火焰喷焊层的显微组织与抗磨粒磨损性能，并对其磨面形貌进行了ＳＥＭ观察分析。结果表明，在Ｎｉ６０自熔性合金中加入适量的镍包ＷＣ粉末可明显提高其喷焊层的抗磨粒磨损性能。当ＷＣ的加入量为３５％（ｗｔ）左右时，该喷焊层与６０Ｓｉ２Ｍｎ调质钢相比，相对的耐磨性可提高６倍以上。     

形状因子对金属橡胶结构力学性能的影响

以多孔材料理论为基础,建立金属橡胶结构的力与位移关系,通过空心圆柱形金属橡胶结构力与位移关系试验,验证形状因子对材料结构的力学性能的影响,并对试验数据进行拟合,得到力与位移关系模型中各项系数与形状因子的变化关系式以及各项系数与材料结构的高度、承载面积的变化关系式,从而实现了对由金属橡胶材料所组成的结构在密度一定、形状因子发生变化情况下的力与位移关系的预估.     

Mg对原位合成TiC-Al2O3/Al复合材料组织与耐磨性的影响

以TiO2,C,Al和Mg粉为原料,原位合成TiC-Al2O3/Al基复合材料。采用XRD和SEM及磨损实验等手段研究Mg对复合材料微观组织及耐磨性的影响。结果表明:Mg影响反应过程及第二相分布,随着Mg含量的增加耐磨性逐渐增加,当预制块中镁为1.0%(质量分数)时,第二相分布弥散、细小,其颗粒尺寸约为2μm,耐磨性最好,磨损量仅为基体的1/6,继续增大Mg含量,由于生成大量粗针状Al3Ti,复合材料的耐磨性反而降低。     

Mechanical and Abrasive Wear Properties of Anodic Oxide Layers Formed on Aluminium

Aluminium oxide coatings were formed on aluminium substrates in oxalic acid-sulphuric acid bath.Abrasion tests of the obtained anodic layers were carried out on a pin-on-disc machine in accordance with the ISO/DP 825 specifications.The Vickers microhardness,D(HV0.2),and the abrasion weight loss,Wa(mg) were measured.Influence of oxalic acid concentration(Cox),bath temperature(T) and anodic current density(J) on D and Wa has been examined,and the sulphuric acid concentration(Csul) was maintained at 160 g·L-1....     

磨料浆体射流磨粒循环使用的加工特性

为了寻求磨料循环有效使用的最佳经济运行策略,通过对2种粒径分布不同、平均粒径相同的碳化硅磨料进行循环使用,研究磨料在不同的循环周期内磨料自身特征的改变及加工性能的改变。结果表明:大颗粒磨料对材料表面的加工起主导作用的是冲击作用,小磨粒对材料的去除主要依靠耕犁和划痕作用;材料切削深度随着磨料循环次数的增加而减小,加工表面粗糙度随着磨料循环次数的增加而变差;在实际生产加工过程中,磨料只适宜循环使用1次。     

Mechanical Strength of Silicon Wafers Cut by Loose Abrasive Slurry and Fixed Abrasive Diamond Wire Sawing

This paper reports on the mechanical strength of polycrystalline silicon wafers cut by loose abrasive slurry and fixed abrasive diamond wire sawing processes. Four line bending and biaxial flexure tests are used to evaluate the fracture strength of the wafers. Fracture strength of the wafers depends on the location, size, and orientation of microcracks in the silicon wafer and the distribution and magnitude of applied stresses. Measurement of microcracks at the wafer edge and center shows that edge cracks are typically larger than center cracks. Fixed abrasive diamond wire sawn wafers are found to have a higher crack density but smaller average crack length. Wafer fracture in four line bending is found to be primarily due to the propagation of edge cracks while center cracks are found to be the primary cause of wafer failure in biaxial flexure tests. Fracture mechanics based analyses demonstrate that crack orientation plays a significant role in four line bending, but not in biaxial flexure. Correlations of the wafer fracture strength and critical crack length agree well with microcrack measurements. The fracture strength of diamond cut wafers is found to be comparable or superior to the strength of slurry cut wafers.     

喷磨试验仪法测定阳极氧化膜的平均耐磨性标准解析

喷磨试验仪法是阳极氧化膜耐磨性的测定方法之一,它可以测量阳极氧化膜的平均耐磨性,并进行分层检验。通过对比国内外和新旧版喷磨标准,讨论了GB/T 12967.1—2008标准修订过程中改进完善的几个方面。通过对取样和磨料等方面的修订,使新版标准具有更强的普遍适用性。     

喷磨法测定铝合金阳极氧化膜耐磨性的影响因素

铝合金阳极氧化膜的耐磨性反映了膜层对摩擦作用的抵抗能力,是氧化膜的一个重要质量指标,可通过喷磨试验来进行测试。考察了测试压力、测试角度、测试距离等对喷磨试验结果的影响。结果表明:喷磨时间随着测试角度的增大而减少,随着测试压力的增大而减小,随着测试距离的变化出现先减少后增加的趋势。对于不同的试样,应选择合适的试验参数来进行检测。     

Fe和Ce 含量对Galfan合金力学性能及耐蚀性的影响

将真空熔炼的Zn-Fe-Ce中间合金加入到Zn-Al熔池中,制备Zn-5Al-0.1Ce-xFe和Zn-5Al-yCe-0.1Fe合金,分析了Fe和Ce含量对合金显微组织及力学性能的影响,并使用电化学工作站测试了合金的电化学性能。结果表明,在Zn-5Al-0.1Ce合金中Fe含量大于0.02%后会形成颗粒状的FeAl3Znx相。随着Fe含量的增加,FeAl3Znx相和先共晶的η-Zn相增加,Zn-Al共晶组织由层片状向点状转变。添加0.1%以下的Fe可提高Galfan合金的抗拉强度。但随着Fe含量的增加,合金的抗拉强度略有降低,Zn-5Al-0.1Ce-0.02Fe合金的综合力学性能最好。添加0.04%以下的Fe会提升合金耐蚀性。此外,随着Ce含量的增加,Zn-5Al-yCe-0.1Fe合金的抗拉强度有所降低,耐蚀性变化不明显。因此,在生产中需要根据镀层性能要求,严格控制合金液中的Fe和Ce含量。     

The Effect of Gunshot Injuries of the Bone Tissue on Its Mechanical Characteristics

Strength of Materials - The results of a developed full-scale biomechanical bench test procedure are analyzed, which makes it possible to determine the changes in the mechanical characteristics of...     

Effect of Hydraulic Liquid and Sea Water on the Mechanical Characteristics of Polymeric Fibrous Structures

Strength of Materials - The degradation of the mechanical characteristics of typical composite materials under the action of the working liquid is studied. Polypropylene and epoxy specimens...     

Modeling of the Wear Resistance of Epoxy Composites According to Changes in Their Mechanical Characteristics

Materials Science - Due to the complex of their physicomechanical and operating characteristics, the composite materials based on thermosetting polymers are extensively used in all branches of...     

Effect of Strain Rate on Discontinuous Flow and Mechanical Characteristics of High-Nitrogenous Steel

Experimental study on the effect of strain rate on discontinuous flow and mechanical characteristics of the high-nitrogenous steel Kh23AG19F has been performed. Within the range of strain rates from 4.62 · 10^-5 to 1.85 · 10 ^-4 s^-1, discontinuous flow, reflected by serration on the tensile diagram, is chiefly determined by intergranular deformation mechanisms. Under strain rates over 1.85 · 10^-2 s^-1, combined deformation modes prevail, which cause a change in the character of discontinuous flow and transform a serrated tensile diagram into a wavy graph, with the yield stress of steel increased significantly.     

B4C对铜基复合材料的力学性能与抗氧化性的影响

用粉末冶金的方法制备了含B4C的铜基复合材料,并研究了B4C加入量及其颗粒粗细对其力学性能与抗氧化性的影响.结果表明,加入B4C的含量(质量分数,下同)≤3%时,可提高材料的硬度、耐磨性,但影响材料的抗氧化性,加入B4C≤2%时,对抗氧化性的影响较小.所以B4C的加入量为2%时,对材料的整体性能影响最佳.B4C颗粒越细,材料的硬度越大,耐磨性越好,抗氧化能力越好.     

低压等离子喷涂MoB/CoCr涂层的组织及耐磨性

采用低压等离子喷涂技术(LPPS)制备MoB/CoCr涂层,对涂层进行磨粒磨损试验研究。采用SEM观察涂层的表面和截面形貌,显微硬度计测试涂层的力学性能,湿式橡胶轮磨粒磨损试验机测试涂层的磨粒磨损性能。结果表明,涂层组织致密,呈层状结构;涂层具有良好的力学性能,显微硬度达到930HV0.3,结合强度在71MPa以上,具有较高的耐磨性能。