TiC-Ni系高温自润滑金属陶瓷的研究

本文利用中频热压烧结法制备了TiC-Ni、TiC-Ni-Mo和TiC-Ni-MO-WC3种高温自润滑性金属陶瓷材料。栓-盘摩擦磨损试验结果表明,TiC-Ni-Mo金属陶瓷的高温自润滑性最好,其在600℃时的摩擦系数为0.19,磨损率为1.14×10~(-14)m~3/N·m,偶件(材料W18Cr4V,HRC62)的磨损率为0.069×10~(-14)m~3/N·m。作者指出,这类材料的高温自润滑性与其摩擦表面上生成的氧化膜的组成和结构相关。此外,本文还就Mo、WC对材料物理机械性能的影响进行了探讨。     

一种镶嵌自润滑轴承的特性研究

本文阐述了一种镶嵌自润滑滑动轴承的性能及特点。考察了载荷和速度等可控因素对这种轴承摩擦系数的影响。试验表明,这种轴承在所用的试验条件下,其摩擦特性基本上不受载荷(P或比压p)和滑动速度(v)的影响。通过实验得到的p-v曲线表明,它符合极限pv值等于常数的规律,並通过统计分析得到了这种轴承在不同可靠度(R)下的极限pv值(当R=50％时,其极限pv值为6.87×10~7Pa·m/min)。还讨论了镶嵌轴承的失稳机理。 为了便于比较,同时介绍了锡青铜轴承的特性试验,结果表明镶嵌轴承在工作速度v<0.32m/s时(本试验条件下)承载能力高于锡青铜轴承的,说明这种轴承适用于低速重载条件下工作。     

微孔贯通型高温自润滑金属陶瓷的摩擦磨损性能研究

以TiH2和CaCO3为复合造孔剂,以硬质微细颗粒为惰性弥散质点,采用真空烧结法制备出具有贯通型微孔结构的Al2O3-Ni-Cr-Mo-Si-Fe系金属陶瓷烧结体,并在烧结体中浸渍Ag-Cu-Pb-Sn系浸渍型固体润滑剂制备出新型高温扩散自润滑材料.结果表明:该材料具有良好的高温自润滑和耐磨性;在600℃下与不同配对材料进行摩擦磨损试验时,摩擦系数变化范围为0.22～0.29,磨损率变化范围约为(6～7)×10-15m3/N·m;润滑膜主要由浸渍在贯通型微孔中的浸渍型固体润滑剂通过微孔向摩擦表面的扩散、并在高温摩擦条件下被软化或熔化而形成.     

锡青铜镶嵌固体润滑剂轴承的摩擦学特性

在栓－盘式端面摩擦磨损试验机上于常温干摩擦条件下，对锡青铜轴承和镶嵌固体润滑剂（ＰＴＦＥ和石墨等复合物）的锡青铜轴承进行了摩擦学性能的对比试验研究．结果表明，几种固体润滑剂嵌入量不同的镶嵌轴承的摩擦系数都明显降低，耐磨性均比对照轴承的高２个数量级，其中以固体润滑剂嵌入面积分数为３０％的轴承的摩擦磨损性能最好．利用Ｘ射线微区分析仪、扫描电子显微镜和能量色散谱仪等，对磨损表面和磨屑的形貌、表面转移膜和元素的面分布等作了观察与分析，指出摩擦界面，尤其轴承金属摩擦表面固体润滑剂转移膜的形成是提高轴承性能的关键，锡青铜镶嵌固体润滑剂轴承以粘着磨损和疲劳磨损为主要磨损机理     

石墨对聚四氟乙烯镶嵌轴承摩擦学性能的影响

作者利用端面摩擦试验机考察了几种石墨与聚四氟乙烯复合固体润滑剂镶嵌锡青铜材料的摩擦磨损性能，发现石墨的添加不仅可以提高聚四氟乙烯镶嵌铀承的耐磨性，而且还可以降低和稳定摩擦系数。通过Ｘ射线衍射、Ｘ射线光电子能谱和电子探针等对摩擦表面转移膜的化学组成和主要元素含量的变化及表面形貌的分析观察，作者认为石墨的减摩作用是其促进聚四氟乙烯向摩擦表面转移并使之在轴承表面形成均匀覆盖的固体润滑剂转移膜，从而有效地     

聚酰亚胺复合材料的摩擦性能及其机理研究

研究了含有固体润滑剂的炭纤维增强 PI复合材料在干摩擦和水润滑 2种状态下的摩擦磨损性能及其磨损机理 .结果表明 ,在水润滑条件下 ,摩擦系数和磨损率都有不同程度的降低 ,其中含 PTFE的炭纤维增强 PI复合材料的耐磨性最佳 ,最低磨损率为 9.9× 10 - 7mm3/ N· m.其主要原因可能与材料存在极性酰胺基团有关 ,酰胺基易通过氢键与水分子结合 ,在摩擦表面形成水吸附膜 ,使摩擦表面直接接触减少 ,从而改善材料的摩擦磨损性能     

铝基镶嵌材料的磨损特性及耐磨机理

制备了镶嵌硬质金属和固体润滑剂的铝基复合材料,通过设计不同的摩擦配副方式,研究了铝基镶嵌复合材料在室温、干摩擦条件下的摩擦学特性。研究结果表明：镶嵌材料的硬度越大,铝基复合材料的耐磨性越高;而镶嵌固体润滑剂并不能有效地改善铝基材料的耐磨性,对铝基复合材料的耐磨机理进行了力学分析,为铝质材料的摩擦学应用指明了新的途径。     

干摩擦条件下铜-石墨复合材料与ZQAl9-4铝青铜的磨损图研究

考察了铜-石墨复合材料和商品ZQAl9-4铝青铜材料在干摩擦条件下的室温摩擦磨损性能,得出了两者的磨损图.结果表明:铜-石墨复合材料表现出优异的减摩性能;铜-石墨材料的磨损体系可以分为轻微磨损(磨损率小于1×10-4 mm3/m)、中等磨损(1×10-4~1×10-3 mm3/m)和严重磨损(磨损率大于1×10-3 mm3/m)3个区域,而ZQAl9-4铝青铜的磨损体系可分为轻微磨损、中等磨损和咬合3个区域;在载荷小于5 N,滑动速度处于0.005~0.05 m/s时,铜-石墨复合材料表现出比铝青铜更优异的耐磨性.     

Ti3SiC2/Inconel718摩擦副的高温摩擦学性能

本文考察了Ti3SiC2-Inconel 718摩擦副从室温到800 ℃范围内的摩擦磨损性能.结果表明:温度的升高有利于改善Ti3 SiC2-Inconel 718摩擦副的摩擦磨损性能,在800℃时,其摩擦磨损性能优异.随着温度的升高,摩擦系数从室温的0.71降至800℃时的0.37,Ti3SiC2的磨损率从4×10-3 mm3/(N·m)降至10-5mm3/(N·m)以下.高温塑性变形和摩擦氧化物层的形成导致摩擦系数的降低,300℃以下,晶粒的断裂、拔出与脱落以及材料向合金的转移造成了Ti3SiC2高的磨损率,从400℃至800℃,Ti3 SiC2晶粒的断裂与脱落受到明显抑制,其磨损率显著降低.     

镶嵌用固体润滑剂对锡青铜轴承摩擦学性能影响的研究

用端面摩擦试验机考察了几种镶嵌用固体润滑剂及添加剂在常温条件下对锡青铜轴承摩擦磨损性能的影响,并用X-射线衍射法、俄歇电子能谱法分析了摩擦表面转移膜的化学组成和结合情况。结果表明,几种固体润滑剂的嵌入均可提高轴承的耐磨性,并对减小摩擦系数有一定的作用;摩擦表面固体润滑剂转移膜的形成能够有效地减少摩擦副表面间的粘着现象,是改善轴承摩擦磨损性能的主要原因。     

ON SOME PROPERTIES OF LIENARD SYSTEMS

ＩｎｔｒｏｄｕｃｔｉｏｎＣｏｎｓｉｄｅｒａｇｅｎｅｒａｌｉｚｅｄＬｉｅｎａｒｄｓｙｓｔｅｍｓｏｆｔｈｅｆｏｒｍ ｘ=ｈ(ｙ) -Ｆ(ｘ) , ｙ=-ｇ(ｘ) ,( 1 )ｗｈｅｒｅｔｈｅｆｕｎｃｔｉｏｎｓＦ ,ｇａｎｄｈａｒｅＬｉｐｓｃｈｉｔｚｃｏｎｔｉｎｕｏｕｓａｎｄｓａｔｉｓｆｙＦ( 0 ) =ｈ( 0 ) =0 ,ｘｇ(ｘ) >0 ,　　ｘ≠ 0 . ( 2 )Ｔｈｅｒｅｈａｖｅｂｅｅｎｍａｎｙｓｔｕｄｉｅｓｆｏｒｌｏｃａｌａｎｄｇｌｏｂａｌｐｒｏｐｅｒｔｉｅｓｏｆｓｏｌｕｔｉｏｎｓｆｏｒｓｙｓｔｅｍ ( 1 ) ,ｓｅｅ[1 -9] .ＳｅｔＣ+=(ｘ,ｙ)｜ｈ(ｙ…     

On the strong singular method for the problems of subsonic flow past obstacles

The purpose of this paper is to give a new investigation on the doublet elementary solution method of solving the problem of subsonic flow. A strong singular integral equation is produced. The definition and the calculating formula of the effective principle value of strong singular integral are given. From this integral equation, some numerical methods corresponding to the whole continuous distribution of elementary solution can be deduced. This method is applicable to calculating subsonic aerodynamic force.     

油溶性铜纳米微粒作为液体石蜡添加剂的摩擦学性能研究

采用液相化学还原法在溶液中原位合成了有机化合物表面修饰铜纳米微粒,用航向电子显微镜表征了微粒的尺寸、形貌和结构,在四球摩擦磨损试验机上考察了其作为液体石蜡添加剂的摩擦学性能,并与二烷基二硫代磷酸锌（ＺＤＤＰ）进行了对比,结果表明：铜纳米微粒添加剂能够显著提高基础油的极压性能,同时具有良好的抗磨性能,尤其是在高负荷下其性能优于ＺＤＤＰ,采用ＥＰＭＡ和ＸＰＳ对铜纳米微粒的极压抗磨机理进行了分析,发现在     

Flow properties of fine powders in powder coating

Three types of nanoparticles and their combinations were blended into a fine powder,which has been used in the powder coating industry.To study their effects on flow properties,the modified powder samples were characterized using a variety of techniques that tested the powder under different powder states ranging from dynamic to static.It was found that all three nanoparticles improved the flow properties of the powder to some degree,though the amounts of the nanoparticles needed were different depending on...     

采用压痕实验获得材料性能的研究现状

本文综述了采用压痕实验获得膜基体系中薄膜弹性，塑性，蠕变性能的研究进展，并指出了目前研究中存在和需要解决的问题。     

In situ synthesis of magnetic mesoporous silica via sol-gel process coupled with precipitation and oxidation

A novel method was proposed for the in situ synthesis of magnetite-containing mesoporous silica SBA- 16 via a sol-gel process coupled with precipitation and oxidation. The effect of the added amounts of reactants on the mesostructural and magnetic properties of the magnetic mesoporous silica was investigated. It was determined that the synthesized magnetic mesoporous silica with a total pore volume of 0.64-0.96 cm 3 /g and an average pore diameter of 4.0-14.9 nm had a relatively high saturation magnetizatio...     

Dissolution and Seepage Coupling Effect on Transport and Mechanical Properties of Glauberite Salt Rock

Potential high rates of aqueous dissolution are characteristic of salt rocks, and solute and mass flux through a soluble porous medium are functions of solute concentration gradients and pressure gradients. Due to different dissolution properties for different mineral components in glauberite salt rock, an interaction between mineral dissolution and solvent seepage arises, driven by the hydraulic pressure gradient in the rock. The originally almost impermeable glauberite rock becomes an increasingly permeable porous medium with dissolution, changing the transport and mechanical properties because of the progressive removal of solid sodium sulfate (Na₂SO₄), one of the constitutive components of glauberite salt rock. Glauberite is often found in bedded salt rock deposits, and the mineral glauberite has economic value and has been mined for many years in China. More economic and safe technologies, such as controlled solution mining, are inherently attractive. Thus, investigations into relevant physical and mechanical properties of glauberite in the context of solution mining have value, and to clarify glauberite behaviour, a series of experiments were performed. It is observed through experiments that the permeability of the rock mass during dissolution of glauberite is a function of the dissolution duration and the hydraulic pressure gradient applied to the system. For example, in laboratory tests, after 49, 53 and 70 h of dissolution, the relationships between permeability (k—cm²) and pressure gradient (Δp—MPa across the specimen of length 100 mm) of the glauberite specimens were observed to be k = 0.24 for a Δp of 0.10, k = 0.30 for a Δp of 0.12, and k = 0.41 for a Δp of 0.18, with the empirical functional relationship becoming gradually steeper with pressure. Also, the triaxial compression (mechanical) characteristics of glauberite salt rock change substantially after a period of dissolution: the compressive strength under a confining stress of σ₃ = 2.0 MPa changes initially from 46 to 11 MPa after 70 h of dissolution and seepage. Along with strength degradation, the Young’s modulus (stiffness) changed from 4.6 to 0.5 GPa. Evidently, coupled dissolution and seepage rate greatly impact both transport and mechanical properties of the rock as fabric evolves in a time-dependent manner.     

稻壳粉含量对树脂基复合材料摩擦学性能的影响

为促进制动摩擦材料环保化及废弃材料再利用,以不同含量的农业副产品稻壳粉为填料,改性酚醛树脂为基体,竹纤维、镁盐晶须和硫酸钙晶须为增强相,石墨和铜粉为摩擦性能调节剂,采用热压成型方法制备新型环保摩擦材料,并对复合材料的力学性能和摩擦学性能进行研究.结果表明:随着稻壳粉含量的增加,试样的冲击强度先增加后下降,而洛氏硬度不断减小.摩擦系数随稻壳粉含量的增加先增大后降低,在高温阶段,稻壳粉填料可以促进摩擦层的形成,稳定摩擦系数,改善热衰退性能,提高耐热性和热稳定性.稻壳粉质量分数为15%时其综合性能最好.     

时效处理对AA2099铝锂合金摩擦学行为的影响

研究了固溶及不同时效状态AA2099铝锂合金的力学性能、摩擦学行为及机理.结果表明:随时效时间的延长,摩擦系数先降低后升高,时效35 h时摩擦系数最低(0.137);磨损量单调减少,时效96 h合金的磨损率最低,为1.7×10–3 mm3/(N·m).固溶态和不同时效态的AA2099铝锂合金主要磨损机制均为磨粒磨损和黏着磨损.摩擦产物对摩擦系数有重要影响,时效35 h的合金摩擦产物分布均匀且连续,具有良好的减摩作用;合金的力学性能与磨痕浅层结构稳定性共同影响合金的磨损率,时效时间小于35 h,合金表面易形成发生剥落的结构,磨损量变化与传统认为的H/E变化不符,但随时效时间进一步延长,剥落减少,磨损量与H/E变化正相关.