用一种新的机理解释电控摩擦效应的几个规律

用电控摩擦的机理——水的电解造成摩擦副接触点附近pH值的升高从而引起金属表面的变化，解释了电控摩擦研究中发现的几个规律：(1)电控摩擦效应的电极电势或电压阈值问题；(2)辅助电极对电控摩擦的影响规律；(3)润滑液对电控摩擦的影响。通过对这些现象的圆满解释进一步验证了该机理的正确性。     

电控摩擦技术的研究进展

作为一种主动控制摩擦性能技术,电控摩擦技术可解决实际中的电接触摩擦问题和主动控制摩擦副的摩擦与磨损性能。综述电控摩擦技术的研究进展,介绍该领域已形成大量的理论体系,如自生电势、表面转移膜、化学反应膜等,展望电控摩擦技术的发展方向。微型化是机电系统的发展趋势,同时也是电控摩擦技术的研究趋势;在微机电系统或纳米机电系统领域,微电控摩擦技术或纳米电控摩擦技术有很好的应用前景。     

一种水基切削液的电控摩擦性能

在改进的球盘式摩擦磨损试验机上，采用辅助电极的加压方法，考察了不同极性、不同幅值的电压对一种水基切削液润滑的GCr15／45钢副摩擦系统摩擦磨损性能的影响。结果表明该水基切削液具有较好的电控摩擦性能。外加电压的极性和幅值对摩擦副电摩擦性能有明显的影响，其作用效果主要取决于系统电化学反应形成的边界膜的性质。     

切削润滑液对车削噪声及表面质量的影响

在切削加工中， 使用切削液润滑，可减小刀具与工件面之间的摩擦，从而减小振动，减小切削噪声。配制适当的切削液，可使切削过程中的噪声降到机床本底噪声以下，工件表面质量也有明显提高。     

无机盐阴离子对果胶水基润滑液减摩性能的影响

利用微摩擦磨损试验机评价果胶作为水基润滑添加剂的摩擦学性能,采用扫描电子显微镜分析磨痕表面形貌,并采用能量色散光谱仪分析摩擦磨损机制。同时还考察工业用水中存在的阴离子对含果胶水基润滑液摩擦学性能的影响。结果表明:在去离子水中加入少量的果胶就可显著改善水的摩擦学性能,并且随着果胶添加量的增大,减摩性能得到进一步提高,这主要是由于果胶在表面吸附形成的润滑膜起到良好的减摩效果;不同阴离子对果胶的摩擦学性能具有不同的影响,其影响的实质是盐析作用和吸附作用。     

Mo2S水基润滑液的摩擦学性能研究

将球磨法制备的超细Mo2S微粒分散于水中形成水基润滑液．用四球摩擦磨损试验机考察了Mo2S水基润滑液的摩擦学性能，用X射线光电子能谱分析了钢球磨损表面典型元素的化学状态。结果表明，Mo2S微粒水基润滑液具有良好的承载能力和抗烧结能力。     

铝材料加工冷却润滑液

在机械制造业,特别是汽车工业中,铝材料由于重量轻,加工性能好而得到日趋广泛的应用。为了满足现代工业对加工精度、表面粗糙度、切削速度、经济性及环境保护越来越高的要求,除了应用现代化的加工设备外,还必须对冷却润滑材料进行探讨和选择。铝合金材料切削加工性能的几个主要指标是,对于不可固化的可锻材料和软态可固化的材料:切屑形状呈长的连续切屑;可提高强度的合金元素,如镁等可改善切屑形状;刀具寿命:即使在切削速度高时,也能保持较长的寿命;切削力小;表面状态:大多数情现下表面质量较差,特别是在材料软时,表面质量更     

外加电场对3种陶瓷/金属摩擦副摩擦行为的影响

使用自制面接触往复式滑动摩擦磨损实验机,采用质量百分比浓度为１％的硬脂酸锌水基乳化液作为润滑剂,研究了边界润滑状态下外加直流电场的几处施加方式对３种摩擦副在低速滑动时摩擦行为的影响。实验结果显示,外加电压的存在显示地改变了３种摩擦副的摩擦系数以及摩擦系数曲线的平稳程度,摩擦系数是最大相对增加量和最大相对减少量分别达到２００％和４０％。摩擦系数的改变与外加直流电压的通断是对应的,不同摩擦副对电压接通     

不平衡量对转子碰摩振动的影响

建立了与限位器碰摩的转子动力学方程 ,用数值积分方法得到了碰摩非线性动力响应。分析中考虑了陀螺效应 ,采用分段线弹性和库仑摩擦模型描述碰摩力。研究双频进动、局部碰摩、拟整圈碰摩和整圈碰摩的振动特征。讨论了不平衡量和激振力幅度变化对碰摩振动形式和特征的影响 ,并给出碰摩振动试验结果 ,以验证数值分析结论。     

DESIGN AND FABRICATION OF , SUPER-HYDROPHOBIC SURFACES ON SILICON WAFERS AND STUDY OF EFFECTS TO HYDROPHOBICITY

Some superhydrophobic siliconbased surfaces with periodic square pillar array microstructures were designed and fabricated, also their apparent contact angles （CAs） were quantitatively measured. On the basis of the classical Wenzel＇s theory and Cassie＇s theory, two generally applicable equations corresponding of the cases of wetted contact and composite contact, which could reflect the relations between geometrical parameters of square pillar microstructures and apparent CAs, were educed. Then a theoretical prediction of the fabricated siliconbased surfaces was carried out by the equations, which was compatible with the result of experimental measurement, and this showed the rationality of the educed equations. The CAs of the surface prepared by merely plasma etching to create microstructures and by only Teflon treating were compared, and the result indicated that the effect of the former on achieving hydrophobic surfaces was greater than that of the later. Under the premise of synthetically considering transition between the two contact states, the effects of geometrical parameters of the square pillar microstructures to hydrophobicity were analyzcation, thereon a design condition and a design principle for super-hydrophobic surfaces which would be of specific application value were summarized.     

材料摩擦因数的可控性研究

在边界润滑状态下采用轴承钢、黄铜等不同摩擦副材料,对一些通用和特殊润滑材料在外加电场作用下摩擦因数的变化进行试验研究,探讨了它们的摩擦控制性能。结果表明：尽管外加电场都能改变这些润滑剂的摩擦因数,但只有BH－1型铁磁流体具有比较理想的摩擦控制性能,说明摩擦可控性并不是润滑材料普遍具有的性质。     

有机硅酸盐对45钢和灰铸铁HT150摩擦性能的影响

运用改装的摩擦试验机对45钢——灰铸铁HT150摩擦副做旋转对磨试验。在摩擦副中加入有机硅酸盐试剂, 在变载荷、定转速条件下在大气环境中进行试验。主要探索有机硅酸盐材料对45钢摩擦副表面改性的机理和耐磨规律。试验发现45钢摩擦试样表面有一层光滑、平坦的乳白色膜生成,微观发现有的区域有大量小质点镶嵌,表面微区亦增添了来自有机硅酸盐中的元素,显微硬度明显提高,表面粗糙度显著降低。起到了良好的减摩耐磨效果。     

微量润滑油润滑和冷风冷却加工法对高硅铝合金切削面的影响

由于高硅铝合金中含有大量硅结晶粒子,硬度较大的硅结晶粒子在切削中会加速刀具的磨损,所以,其被切削性非常不好。为解决这一问题,以往是使用大量切削油进行切削加工。但是,随着环境意识的提高,大量切削油的使用所造成的环境污染的问题不得不被认识并进行改变。使用对切削点进行微量植物性润滑油润滑和冷风冷却的方法进行研究,探讨对高硅铝合金切削面的影响。并因此探讨半干式切削加工的可行性。     

叶片正弯曲对涡轮静叶栅流场影响的试验研究

对一典型涡轮静叶型开展了叶片正弯曲对涡轮叶栅流场性能影响的试验研究。测量了直叶栅和 +10°、+2 0°、+30°弯曲叶片叶栅出口流场。结果表明 ,对该叶型叶栅 ,随着叶片正弯曲角的增加 ,通道涡一直位于叶栅端壁附近 ,其强度变化很小 ,但叶栅出口尾缘涡明显增强 ,并向叶栅中部扩展 ;同时 ,随着叶片正弯曲角的增加 ,叶栅端部总损失变化不大 ,但叶栅中部总损失迅速增加 ,导致叶栅总损失随叶片正弯曲角的增加而增大 ,直叶片叶栅总损失最小     

叶片反弯曲对涡轮静叶栅流场影响的试验研究

对一典型涡轮静叶型开展了叶片反弯曲对涡轮静叶栅流场性能影响的试验研究。测量了直叶片叶栅和-10°、-20°弯曲叶片叶栅出口流场。结果表明,对该叶型叶栅,随着叶片反弯曲角的增加,叶栅出口通道涡的强度和尺度稍有增大,但位置变化不太明显,尾缘涡有所减弱,叶栅中部和端部横向二次流均增强;随着叶片反弯曲角的增加,叶栅中部损失变化不大,而端部附近损失明显增大,使叶栅总损失增大,直叶栅总损失最小。     

EFFECT OF SURFACE ENERGY ON THE GROWTH OF DIAMOND-LIKE CARBON/AMORPHOUS SILICON FILMS ON VARIOUS SUBSTRATES

Diamond-like carbon/amorphous silicon bilayer films were deposited on SiO₂, Ge, and Ta₂O₅ substrates using a pulsed filtered cathodic arc (PFCA) system. Amorphous silicon (a-Si) layer was firstly deposited on three substrates using DC magnetron sputtering, then diamond-like carbon (DLC) film was deposited on a-Si layer via pulsed filtered cathodic arc. The thicknesses of a-Si layer and DLC film as monitored by in-situ ellipsometry during the film deposition were 7 and 10 nm, respectively. The surface energy of SiO₂, Ge, and Ta₂O₅ substrates was determined by measuring the contact angle of water on these substrates. It was found that the contact angles of water on SiO₂, Ge, and Ta₂O₅ substrates were 53°, 63°, and 75°, respectively. This result indicates that SiO₂ has the highest surface energy while Ta₂O₅ has the lowest surface energy. The thickness of the a-Si layer and DLC film was determined from the cross-section transmission electron microscopy (TEM) images. The thinnest a-Si layer of 5.64 nm was obtained from SiO₂ substrate which has the highest surface energy. The thickest a-Si layer of 6.97 nm was obtained from Ta₂O₅ corresponding to the lowest surface energy. This study shows that the thickness of the growth film strongly depends on the surface energy of the substrate. However, the DLC films deposited on each a-Si layer of three substrates have the same thickness approximately of 9.9 nm, because all of them were deposited on a-Si layers having the same surface energy.     

ON THE NATURE OF MACHINING CRACKS IN GROUND CERAMICS: PART II, COMPARISON TO OTHER SILICON NITRIDES AND DAMAGE MAPS

The size and severity of grinding machining cracks in a sintered reaction bonded silicon nitride are compared to data for other silicon nitrides. Crack sizes follow a similar trend with grinding wheel grit size despite differences in microstructures, strengths, and fracture toughnesses. Silicon nitrides with enhanced fracture toughness actually develop deeper machining cracks than in less tough silicon nitrides. Machining damage maps for silicon nitride are presented.     

金刚石车刀前角与切削刃钝圆半径对单晶硅加工表层质量的影响

在对单晶硅的超精密切削加工中,为了优化金刚石刀具参数以利于实现其塑性域切削,运用线弹性断裂力学和有限元法对在不同的刀具前角和切削刃钝圆半径下切削区域的应力场分布和微裂纹扩展规律进行了计算仿真研究,并在此基础上进行了单晶硅的金刚石切削试验以验证仿真分析。结果表明,采用前角范围为-15°～-25°的车刀进行切削有利于抑制原子级尺寸裂纹初步扩展成微裂纹,因此可以提高加工时的脆塑转变临界切深值,有利于实现塑性域切削;而且,切削刃钝圆半径越小加工时的微裂纹就越不易扩展,因此也就容易实现单晶硅的塑性域车削,得到高质量的金刚石切削加工表面。