304 不锈钢电火花线切割加工表面性能研究

目的研究电火花线切割工艺对金属材料加工表面质量的影响规律,分析加工表面的机械性能。方法利用电火花线切割加工技术,对304不锈钢工件进行表面切割试验,应用马尔轮廓测量仪、扫描电镜、超景深电子显微镜及纳米压痕仪观察电火花加工表面的粗糙度变化规律和表面微形貌特征,获取横截面纳米硬度变化曲线。设计正交试验,获得最优加工参数。结果脉冲宽度和峰值电流对奥氏体不锈钢加工表面形貌的形成机制有显著影响,加工表面粗糙度受电参数的影响较大,加工表面的表层及次表层组织主要由塑性变形层与回火多相组织层共同构成,厚度与纳米硬度的变化受电参数的影响较大。结论电参数对表面质量的影响程度顺序为脉冲宽度、峰值电流、放电间隔,为得到较优加工表面层,应优先选择脉冲宽度为16μs,放电间隔为96μs,峰值电流为1.5 A的工艺参数组合。单个脉冲能量对加工层的厚度以及表层的纳米硬度呈现出近似线性规律。     

电参数对20Mn23AlV无磁钢毛化形貌影响的研究

为了研究电火花毛化加工中电参数对20Mn23AlV毛化表面形貌的影响,用石墨作为电极材料,对20Mn23AlV钢进行电火花毛化正交试验。研究了峰值电流、脉冲宽度和脉冲间隙对20Mn23AlV钢毛化表面形貌的影响。通过扫描电镜观察不同电参数下毛化表面的形貌,分析了峰值电流、脉冲宽度、脉冲间隙对毛化表面形貌的影响。最后总结了无磁钢板电火花毛化加工选择电参数的原则。结果表明:在满足电火花毛化工艺要求的条件下,选用较低的峰值电流和脉冲宽度,分别为2.5A和2μs,脉冲间隔为4μs。     

放电参数对线切割加工A8工具钢表面粗糙度与材料去除率的影响

A8工具钢是一种高硬度高韧性的难加工材料,常用电火花线切割来加工处理。电火花线切割加工A8工具钢实际生产过程中,表面粗糙度和材料去除率分别是加工表面质量和加工效率的重要指标,放电参数直接影响到表面粗糙度和材料去除率。在几组生产中常用的放电参数(加工电流、脉冲宽度、脉冲间隙)条件下,加工A8工具钢,分别得到每种放电参数对表面粗糙度和材料去除率的具体影响规律,结果表明:随着加工电流的增大,加工后材料表面粗糙度和材料除去率同时增大且趋势相似;随着脉冲宽度的增大,加工后材料表面粗糙度和材料除去率同时增大;随着脉冲间隙的增大,材料除去率呈递减趋势,加工后材料表面粗糙度前期递减,在脉冲间隔8μs后减小趋势放缓,在脉冲间隔10μs时达到最小值,在脉冲间隔大于10μs后略有升高,变化幅度不大。研究结果为实际生产中电火花线切割加工A8工具钢提供技术参考,可以根据不同的生产要求选择合适的放电参数组合。     

工件超声振动电火花复合加工技术的研究

采用正交试验和信噪比两种分析方法,并基于BP神经网络,研究了工件超声振动电火花复合加工技术的两个重要方面:工艺参数优化和工艺预测模型。研究了间隙电压、峰值电流、脉冲宽度和脉冲间隔对表面粗糙度及加工时间的影响,得到了基于试验数据的预测模型。结果表明,对表面粗糙度影响最大的电参数是峰值电流,然后依次为间隙电压、脉冲间隔、脉冲宽度,最优参数组为间隙电压65V,峰值电流2A,脉冲宽度5μs,脉冲间隔70μs;对加工速度影响最大的电参数是峰值电流,然后依次为脉冲宽度、间隙电压、脉冲间隔,最优参数组为间隙电压65 V,峰值电流8 A,脉冲宽度50μs,脉冲间隔10μs。通过信噪比分析得到的结果与正交试验分析得到的结果基本相同,但信噪比分析的结果比正交试验分析的结果稳定性得到提高。     

电火花毛化加工电参数对无磁钢吸光率的影响

为了研究在小电流、小脉宽条件下电火花加工毛化表面对提高材料表面吸光率的效果,以无磁钢(20Mn23Al V)为研究对象,在电火花成型机床上进行毛化加工,研究了峰值电流和脉冲宽度对吸光效果的影响。结果表明,在小电流小脉宽条件下,吸光率随着峰值电流和脉冲宽度的增加而减小。并通过扫描电镜对毛化表面形貌的观察,对峰值电流和脉冲宽度对吸光率的这种影响关系进行了分析和说明。     

电火花毛化表面电磁屏蔽效能影响因素分析

主要针对电火花毛化表面电磁屏蔽效能的影响因素进行分析。为了研究在大电流、小脉宽条件下电火花加工毛化表面对提高材料表面吸波率的效果,得到较为理想的吸波毛化表面,在数控电火花成型加工机床上进行样件加工。通过积分球吸波试验台,利用其均分测量误差的特性,测量毛化表面电磁波的反射强度和对电火花毛化表面的吸波特性进行定性及定量的分析,并在扫描电镜和金相显微镜下结合表面形貌特征对试验数据的变化规律进行分析,研究脉冲宽度和峰值电流对吸波效果的影响。结果表明:毛化表面对电磁波的吸收情况受表面形貌的影响;在大电流、小脉宽条件下,吸波率随着脉冲宽度的增加呈现先增后减的趋势;吸波率随着峰值电流的增加总体上呈现增大的趋势。     

水下电火花加工工艺研究

采用自行研制的水下电火花加工装置,选用石墨或紫铜作为电极材料、去离子水作为工作液,通过正交试验,利用水下电火花来加工不锈钢;讨论峰值电流、脉冲宽度对于水下电火花加工性能的影响。结果表明:采用石墨作为电极可获得较大的材料加工速度;峰值电流和脉冲宽度对水下电火花加工速度影响最为明显。     

基于微纳乳液的Inconel718电火花成形加工工艺实验研究

采用自制的微纳乳液作为工作液,利用电火花成形加工镍基高温合金(Inconel718),选取峰值电流、脉冲宽度、脉冲间隔及单次加工时间等参数进行十字正交试验,研究分析这些参数对电火花成形加工Inconel718的表面粗糙度和材料去除率的影响,并对比了在微纳乳液与煤油工作液中加工的工件表面微观形貌。结果表明:峰值电流对材料去除率影响显著,单次加工时间对表面粗糙度影响显著;与煤油工作液相比,采用微纳乳液进行电火花成形加工的工件表面质量更好。     

硬质合金YG8A电火花加工工艺试验研究

研究了在YG8A的电火花加工中脉冲宽度、峰值电流等电参数对加工速度、电极损耗、加工表面粗糙度的影响。结果表明,脉冲宽度和峰值电流必须在一个合适的范围内才能得到较好的加工效果。     

SiC/Al功能梯度材料的电火花加工多目标参数优化及回归分析

采用正交试验与灰色关联分析相结合的方法,对Si C质量分数为5%的Si C/Al功能梯度材料进行电火花加工工艺试验,研究了工艺参数对材料去除率、电极相对损耗率的影响,同时建立了工艺参数对材料去除率、电极相对损耗率及综合指标的多元非线性回归方程。结果表明:对综合指标的影响由主到次分别为脉冲宽度、脉冲间隔、抬刀高度、加工电压、峰值电流,优化后的加工参数为峰值电流10 A、脉冲宽度200μs、脉冲间隔50μs、加工电压50 V、抬刀高度3 mm,与参数优化前相比,材料去除率降低约5.8%、电极相对损耗率降低约51.8%。建立的回归模型可为Si C/Al功能梯度材料的电火花加工试验研究提供理论指导。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is e_c~(2.9907) · (s_c~(0.4980) d_c~(2.4927)) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.