缓冲包装系统冲击特性的分析

分析了缓冲包装系统的冲击特性，采用对比法和仿真分析法研究了非线性缓冲包装系统的冲击特性。研究表明，计算机仿真是进行缓冲包装动态特性分析及缓冲包装设计的一种有效方法。     

斜激波与物质界面相互作用的数值模拟

利用多介质PPM方法研究了斜激波与物质交界面的相互作用。采用与体积分数耦合的Euler方程组作为计算模型,用双波近似来求解一般刚性气体状态方程Riemann问题,通过体积分数的计算来获得界面的位置,在整个流场采用统一的高阶PPM格式进行计算。文中对斜激波与不同物质界面相互作用进行了数值模拟,并给出了交界面上由于斜压效应产生的涡列的演化过程,特别是强斜激波与不同物质界面的相互作用情况。     

Dry wear and friction behaviour of plasma nitrided Ti–6AL–4 V alloy after explosive shock treatment

The unlubricated wear behaviour of explosive shock treated and, subsequently plasma nitrided Ti–6Al–4 V alloy was studied using a ball-on-disc wear tester. Plasma nitriding was carried out at three different temperatures (700, 800 and 900 °C) for 3, 6, 9 and 12 h. Plasma nitriding after explosive shock treatment enabled a reduction in the wear rate of two orders of magnitude. Detailed investigations of this improved wear performance dependent on the nitriding temperature and time were carried out. The friction and wear data showed a clear breakthrough transition from the nitrided layer to the core of the Ti–6Al–4 V alloy matrix. The lowest wear volume was obtained for the sample, nitrided at 900 °C for 12 h, especially at loads of 2.5, 5 and 7.5 N. Obviously, the hard nitride layers were intimately associated with low wear rate, providing a smooth low friction surface. The coefficient of friction reduced from 0.46 to 0.2 due to a thick and hard compound layer resulting from a high nitrogen diffusion rate caused by explosive shock treatment that expected to increase point defects in the alloy. Detailed examination of the wear tracks showed that plasma nitriding changes the mechanism of wear from one of adhesion for untreated Ti–6Al–4 V to both delamination and mild abrasive.     

喷丸与激光喷丸强化高强度钢对比试验

为了考察和对比喷丸(SP)和激光喷丸(LSP)2种表面强化技术对金属零件的强化效果,以30CrMnSiNi2A钢为试样,进行喷丸和激光喷丸强化处理试验。试验结果显示,2种强化试样的残余压应力和硬度都有较大的提高。分别测定了喷丸强化和激光喷丸强化试样在同一应力水平下的疲劳寿命,并运用扫描电镜分析了两者的疲劳断口。试验结果表明,激光喷丸强化试样中值疲劳寿命是喷丸强化试样的1.11~2.75倍,激光喷丸强化比喷丸强化在提高金属零件表面性能方面的效果更佳。     

PVTt法气体流量标准装置中标定时间的确定

PVTt法气体流量标准装置是测量气体质量流量的一种高精度标准装置,通过测量装置中标准容器内充气前后的气体压力、温度来确定流过被检表的气体实际质量流量值.该气动系统中的充气过程是热力变化和传热变化的复杂过程.该文运用热力学、气体动力学中喷管及激波理论,研究了标定时间理论值的计算,并进行了实例分析.研究表明启动段时间对测量精度影响甚微,而充气过程中的多变指数n及控制元件(喷管)的选用对测量精度影响较大.     

Sialon陶瓷热挤压模的应用研究

用Ｓｉａｌｏｎ陶瓷取代３Ｃｒ２Ｗ８Ｖ钢进行热挤压模的应用试验，取得良好效果，并对与应用相关的陶瓷材料抗热震性和磨损性能进行了研究。     

陶瓷增强相对金属-陶瓷复合涂层的影响

对电弧喷涂几种不同陶瓷增强相的Fe复合涂层的特点和性能进行了研究，在20钢基体上喷涂含陶瓷TiB2／Al2O3，TiB2-Cr3C2，TiB2，Cr3C2及TiB2-Cr3C2-Al2O3的管状喷涂丝材，采用光学显微镜和XRD对涂层的微观特性进行分析，结果表明，涂层中含有TiB2，Al2O3，Cr3C2，Cr3O2等陶瓷相。通过对涂层常规性能测试表明，含TiB2／Al2O3和Cr3C2的涂层孔隙率较低、结合强度高、并具有优良的耐磨性及抗热震性能。     

不同粘结剂对碳纳米管红外吸收涂层性能的影响

碳纳米管涂层已在低温工作环境中大量应用,所选用的粘结剂在很大程度上影响其红外吸收性能及与基体的结合性能。分别用水玻璃粘结剂和磷酸盐粘结剂与碳纳米管、镍粉混合制成涂料,并将其涂覆在铜基体表面。采用XRD和SEM对涂层的红外吸收性能、物相、晶体结构及形貌进行了表征;测试了涂层的抗热震性能。结果表明:当粘结剂为磷酸盐、含量为90%~85%时,1 400~3 570 cm~(-1)(2.80~7.14μm)波段内涂层的平均光吸收度达1.992~2.084,红外吸收性能最佳,抗热震次数可达35次(25~120℃),满足了用户要求(10次)。     

WC nano-particle surface injection via laser shock peening onto 5A06 aluminum alloy

A novel technique, named nano-particle surface injection via laser shock peening-NPSI/LSP, for surface modification of light alloys is reported. The WC nano-particles were implanted into a 5A06 aluminum alloy surface under a very high pressure (up to Giga or even tens of Giga Pascal), produced by a Q-switched pulsed Nd:Glass laser system. The results confirmed that the surface performance of the 5A06 aluminum alloy have been dramatically improved by the NPSI/LSP process based on an integrated strengthening mechanism of laser shock peening, nano-particles and nano-particle intensified shock peening.     

Condensing Heat Transfer in Steam-Water Condensing-injector

An experiment on the direct heat transfer process between supersonic steam and subcooled water jet was performed, using a steam-water condensing-injector. Photographic observation provided information on the state of flow, and establishment of a critical separate steam-water flow was confirmed. The temperature and pressure distributions along the flow were measured and the effective coefficients of condensing heat transfer were evaluated from the observed data, based on a model embodying an idealized interface between vapor and liquid. In the vicinity of the water nozzle exit, where the vapor-liquid interface was distinct, the heat transfer coefficients obtained were 14–28 (cal/°C.cm².sec), and some correlation was observed among Nusselt, Reynolds and Jakob numbers, upon adopting the velocity and the physical properties of the steam phase. The relations Nu=6.0.Re ^0.9(Pr=1.04–1.10), and Re=1.8×10⁸.Ja ^3.0, i.e., Nu=1.6×10⁸.Ja ^2.7 were derived as a rough estimation. No clear correlation could be discerned in the corresponding data obtained from observation points further downstream, where a distinct steam-water interface no longer existed. In conclusion, it is proposed that, in deriving the correlations between Nu and Re or Ja, the physical properties of the vapor and the vapor-liquid relative velocity should be adopted, on account of the strong dependence of condensing heat transfer on steam velocity and water subcooling.