超声表面滚压技术及其组合工艺现状

概述了USRP在磨损、疲劳以及腐蚀领域的防护现状,并对其防护机理进行了讨论。同时归纳了USRP技术存在的问题,比如当表面强化层的塑性变形程度达到一定的极限时,不仅很难进一步提高材料性能,继续加工更会导致起皱、开裂等表面缺陷的产生,最终致使材料性能恶化。在此基础上,重点综述了组合USRP工艺的研究进展,并按照组合工艺中USRP技术的时间顺序,分为前端组合(超声滚压–等离子渗技术、超声滚压–物理气相沉积技术、超声滚压–微弧氧化技术等)、后端组合(热处理–超声滚压技术、激光冲击–超声滚压技术、激光熔覆–超声滚压技术、激光选区熔化–超声滚压技术等)以及同步复合工艺(电脉冲辅助超声滚压技术、温度场辅助超声滚压技术等)。最后,就USRP技术及其组合工艺进一步的研究和发展方向进行了展望,为USRP后续研究及应用提供技术参考。     

基于逆向技术的奶勺模具设计与制造

以奶勺模具设计与制造为例,阐述了逆向工程的概念与特点,提出了模具逆向设计系统的架构,分析了其在模具设计中的应用技术,研究了基于Pro/Engineer开发的模具设计流程,对数据采集,曲面重构等关键问题做了详细分析.利用这种反求技术实现奶勺模具的设计与制造,可以大大缩短研发,制造周期,提高企业竞争力.     

介孔CeO2的化学沉淀法合成及表征

以硝酸铈(Ce(NO3)3.6H2O)、碳酸铵((NH4)2CO3.H2O)为原料,十六烷基三甲基溴化铵(CTAB)为模板剂,采用化学沉淀法合成了一系列具有不同孔径的介孔CeO2粉末,使用X射线衍射(XRD)、差示/热重(DSC/TG)、BET孔性能测试、透射电镜(TEM)及红外光谱(IR)分析等手段对合成产物进行了分析和表征,探讨了CTAB与Ce的摩尔比、反应温度、焙烧温度和时间对孔径大小和比表面积的影响。在CTAB与Ce的摩尔比为1∶1、反应温度为80℃、焙烧温度为300℃、焙烧时间为1 h条件下,制得了比表面积为132 m2/g的介孔CeO2。     

金属快速凝固的非平衡超急速传热模型

运用非Fourier传热理论建立了金属快速凝固过程中的非平衡传热理论模型，包括非Fourier方程的建立、传热与相变模拟，模拟计算表明：（1）在溅射激冷条件下，界面换热系数越大，界面冷却速度和移动速度也越高。在界面换热系数相同时，计算得到的界面冷却速度随着固－液界面高度的提高呈现先上升而后下降的变化趋势；计算得到的冷却速度值明显小于Fourier定律的计算值。（2）在激光加热条件下，计算的界面移动速度在凝固开始时先急剧增加，然后渐趋平稳，计算还表明，金属的过热及过冷度与其热物性相关。     

机械合金化Ag-30Cr合金在0.1 Mpa纯氧气中的氧化

采用机械合金化方法制备了Cr含量为30％(质量分数)的两相颗粒极细的Ag—Cr合金，在700℃，800℃及0．1MPa纯氧气中氧化时，机械合金化Ag-30Cr合金外层为Ag层，其下方为复合氧化物AgCrO2，最内层为连续的Cr2O3，这一结构不同于粗晶粒粉末冶金Ag—Cr合金的复杂的混合氧化膜。这主要是由于晶粒的细化加快了Cr颗粒的溶解，加速了Cr从合金到膜的扩散，从而有效地促进Cr2O3层的形成。     

高能球磨形成具有明显玻璃转变的Ti50Cu20Ni24Si4B2非晶态合金

在高能球磨作用下，名义成分为Ti50Cu20Ni24Si4B2的元素粉末混合物可通过固态反应非晶化。差示扫描量热分析（DSC）表明，球磨获得的非晶相在发生晶化转变之前出现明显的玻璃转变。过冷液态温度区的宽度（ΔTx）可达到57K。非晶态Ti50Cu20Ni24Si4B2合金加热时的转变由一步完成。同时形成立方结构的（Ni,Cu)Ti相和其它未知相。为共晶型转变。随后发生晶化产物的进一步晶粒长大。非晶态Ti50Cu20Ni24Si4B2合金的约化玻璃转变温度（Trg)为0．56。     

成型砂轮截面曲线光顺处理的近似双圆弧插补法及误差估算

在解决成型砂轮截面曲线的光顺处理问题时，作者提出了一种新的曲线数字化处理方法——近似双圆弧插补法，简化了计算过程。为了估算该方法的误差，本文模拟曲线反求的过程进行了仿真计算，计算结果表明：若曲线反求时测量点的间距取为0．1mm左右，则对所讨论的实例而言，处理结果对原曲线的最大偏离为0．552μm，这样的误差对数控加工影响很小，而且整个处理过程所花费的时间不足1分钟，因此，该方法能满足数控加工的要求。     

The yttrium effect on the corrosion resistance of CO2-laser processed MCrAlY coatings

To improve the corrosion resistance and to study the effect of yttrium in the behavior of coatings produced by thermal spraying MCrAlY (M=Ni, Co) powders, CO₂ laser processing was conducted. Three methods were used: (1) a combination of gas flame and plasma spraying in air followed by laser glazing in argon, (2) low-pressure plasma spraying (LPPS) and laser glazing in argon, and (3) LPPS and laser-gas (O₂) alloying. Laser glazing in argon of the MCrAlY coatings sprayed in air promoted formation of weakly adherent agglomerates of Al–Y oxides and an alumina-chromia solid solution. Glazing in argon atmosphere of LPPS CoNiCrAlY and NiCrAlY coatings caused the formation of nickel aluminides besides the formation of Y–Al compounds. Gas (O₂)-alloying of these coatings produces continuous and adherent (yttrium-containing) alumina and chromia layers. The effects of yttrium on the characteristics of the oxides formed in the coatings during laser glazing, laser-gas alloying, and high-temperature oxidation is discussed. This work also investigated the oxidation resistance of the laser-processed MCrAlY coatings in air and in the presence of 85 mol/o V₂O₅–Na₂SO₄ fused salt at 900°C.     

限幅绝缘盖板注塑模设计

通过对限幅绝缘盖板的工艺分析,确定了开放型腔、滑块脱模的模具结构.此模具构思巧妙,结构简单,不但成功地解决了塑件成型、侧孔贯通、顺利脱模的问题,而且大大降低了模具成本,缩短了研制周期.     

Bio-mimetic surface structuring of coating for tribological applications

A novel multilayered coating was developed for applications associated with friction reduction and wear resistance improvement. The nano-engineered coating integrates a soft lubricating layer, consisting of MoS₂-PTFE, onto hard load-supporting layers, with controlled surface morphology (roughness and patterning) of cBN-TiN. The coating was synthesized by sequential procedures including electrostatic spray deposition of cBN particles with different average particle sizes, chemical vapor deposition of TiN, deposition of nano- and micro-sized MoS₂ dispersed in PTFE, and curing. The effect of cBN particle size (with different combinations of particle size) and deposition parameters (specifically electrical voltage) on the cBN-TiN surface morphology were studied experimentally and optimized. SEM characterization of the as-synthesized cBN-TiN coating shows surface features similar to that of colocasia esculenta, with alternating nano- and micro-sized domes and “pockets”; the MoS₂-PTFE top layer has MoS₂ particles retained in the pockets by a basket structure formed during PTFE curing. Tribological and scratch tests were carried out for the as-prepared cBN-TiN and cBN-TiN/MoS₂-PTFE multilayered coatings. Sliding test results demonstrate significantly lower friction coefficient for the multilayered coating, showing that the unique integration of soft lubricating layer and biomimetically structured hard layer can effectively improve tribological performance. It is suggested that lubrication at the frictional contacts was realized by continuous release of the lubricants, MoS₂ and PTFE, from the pockets.