二维超声磨削复相陶瓷加工表面质量的试验研究

本文通过对二维超声磨削纳米复相陶瓷和普通磨削进行对比试验研究,分析了磨削深度、工件速度、砂轮粒度对工件表面质量的影响.研究结果表明,采用二维超声振动磨削能大大提高工件的表面质量;表面粗糙度随着切深的增大而增大,随着切削深度的进一步增加,超声振动在磨削加工中所起的作用减弱;二维超声振动磨削大大扩大了复相陶瓷磨削的塑性加工区域,二维超声振动磨削过程的塑性域是切削深度小于5μm,而普通磨削塑性域是磨削深度小于2μm;二维超声振动磨削时,表面粗糙度随着砂轮粒度的减小而明显减小,且比较稳定,故二维超声振动磨削有利于使用细粒度砂轮;工件速度对二维超声振动磨削表面粗糙度影响很大,其值随着工件速度的增加而增大.     

二维超声磨削纳米复相陶瓷的磨削特性研究(1)

本文通过对二维超声磨削纳米复相陶瓷的磨削特性进行理论分析及试验研究，尤其是磨削力的特性及其影响因素，从而探索磨削加工表面质量的影响因素并提出改善磨削效果的措施。研究结果表明，磨削力随着切深的增大而增大，随着磨削深度的进一步增加，超声振动在磨削加工中所起的作用减弱；二维超声振动磨削大大扩大了复相陶瓷磨削的塑性加工区域，二维超声振动磨削过程的塑性域是磨削深度小于5μm，而普通磨削塑性域是在磨削深度小于2μm；适当增大磨削速度，既可以增强磨削砂轮的自锐能力，获得较高的去除率，又可以增加塑性变形，改善工件的表面质量；砂轮线速度的变化对二维超声振动磨削过程中的磨削力影响比对普通磨削过程中的磨削力的影响小，故二维超声振动磨削可以选用较大的砂轮线速度；工件速度对二维超声振动磨削表面粗糙度影响很大，其值随着工件速度的增加而增大。     

二维超声振动磨削纳米复相陶瓷的表面粗糙度研究

本文对纳米复相陶瓷材料进行了不同参数下的普通磨削和二维超声振动磨削的对比试验，研究了超声振动磨削对工件表面质量的影响，分析了不同的加工工艺参数及振动参数对加工工件表面粗糙度的影响，实验结果表明，在同样的切深条件下，超声振动磨削表面的沟槽浅而宽，可以得到比普通磨削加工粗糙度较小的加工表面，且在超声振动中砂轮作高频振动，砂轮不易堵塞，利于使用细粒度砂轮磨削；工件速度对二维超声振动磨削表面粗糙度影响很大，其值随着工件速度的增加而增大。二维超声振动磨削可以提高陶瓷材料的表面质量，并能有效地避免普通磨削下微裂纹的产生，因此它是磨削陶瓷的一种精密加工方法。     

粗磨粒金刚石砂轮精密磨削工程陶瓷的试验研究

为了实现粗磨粒金刚石砂轮延性域磨削加工SiC陶瓷材料,采用碟轮对粒径为297~420μm的粗磨粒金刚石砂轮进行了精密修整。然后,使用经过修整好的粗磨粒金刚石砂轮对SiC陶瓷进行磨削加工。在此基础上,对不同的砂轮线速度、工件进给速度、磨削切深对SiC陶瓷表面粗糙度和表面形貌的影响进行了研究。试验结果表明:经过精密修整的粗磨粒金刚石砂轮是能够实现SiC陶瓷材料的延性域磨削的,表面粗糙度值Ra达到0.151μm;随着砂轮线速度增大、工件进给速度和磨削切深减小,SiC陶瓷表面的脆性断裂减小,塑性去除增加。     

超声纵振珩磨表面微观特性的试验研究

在文献[1]中，作者对径向超声振动磨削和纵向（轴向）超声振动珩磨的磨削特点进行了对比研究，建立了磨粒径向超声振动珩磨的切削模型，推导了纵向超声振动珩磨临界速度的计算公式，为了验证所建模型的正确性及进一步研究超声纵振珩磨的磨削表面特征，本文对工程陶瓷ZrO2和高强度P钢进行了纵向超声振动珩磨试验，通过电镜SEM观察分析了表面磨削特征，研究表明：纵向超声振动珩磨具有比普通珩磨较大的材料去除率，并且磨削表面光滑，粗糙度低。     

超声振动磨削放电复合加工SiCp／Al试验研究

针对SiCp／Al的加工,提出一种超声振动磨削放电复合加工的方法．从加工效率、加工稳定性及表面质量等方面与电火花加工进行了对比试验研究。分析了两种加工方法的脉冲宽度和峰值电流对加工速度和表面粗糙度的影响,结果表明：电火花加工的表面粗糙度平均值为尺04．5μm,超声振动磨削放电复合加工的表面粗糙度平均值为Ra2μm：超声振动磨削放电复合加工的稳定性比电火花加工好,但加工速度较低。通过扫描电镜对两种加工方法下零件表面形貌和重熔层进行了观测,对试件表面进行了X射线衍射分析,表明采用超声振动磨削放电复合加工SiCp／Al复合材料可获得较好的表面质量。     

微粉金刚石钎焊砂轮磨削氧化铝陶瓷的磨削力和表面粗糙度特征

在不同磨削深度、砂轮转速和进给速度组合下,研究微粉金刚石钎焊砂轮磨削氧化铝陶瓷过程的磨削力及工件的表面粗糙度的变化规律,并筛选出低磨削力和低工件表面粗糙度的加工工艺参数。试验结果表明:在微粉金刚石钎焊砂轮的磨削过程中,氧化铝陶瓷主要通过脆性断裂的方式去除;随着磨削深度、进给速度的增加,砂轮在进给方向和切深方向的力以及工件表面粗糙度都上升;随着砂轮转速的增加,进给方向和切深方向的力以及工件表面粗糙度都下降。试验获得的低磨削力和低工件表面粗糙度精密加工工艺参数分别为:磨削深度为1.0 μm,进给速度为12 mm/min,砂轮转速为24 000 r/min和磨削深度为1.0 μm,进给速度为1 mm/min,砂轮转速为20 000 r/min。低磨削力磨削时,微粉金刚石钎焊砂轮受到的X方向和Z方向的磨削力分别为0.15 N和0.72 N;精密加工后的氧化铝陶瓷的表面粗糙度值可达0.438 μm。      

航天用SiC反射镜超声振动辅助磨削工艺研究

针对航天用SiC反射镜的低加工效率、表面质量差等难题,采用超声振动辅助磨削技术对其进行工艺实验研究。首先,通过选用树脂结合剂金刚石杯型砂轮并采取栅线式磨削研究不同工艺参数对磨削效率的影响关系。然后采取螺旋式磨削进行正交实验探究超声振幅、进给速度、砂轮转速、磨削深度对表面粗糙度的影响,并采用极差法分析探究各因素对工件磨削质量影响程度的大小。研究结果表明:当超声振幅5μm,进给速度80mm/min,砂轮转速6000r/min,磨削深度2μm时可获得表面粗糙度Ra97nm的已加工表面。     

修整参数对陶瓷cBN砂轮磨削效果的影响

本研究采用陶瓷cBN砂轮加工冷激合金铸铁凸轮,采用金刚石滚轮对砂轮进行在线修整。通过改变修整量、滚轮与砂轮的相对移动速度、修整速比,得出修整参数对砂轮磨削效果的影响规律。研究结果表明,当修整量从5μm×4降低到5μm×3时,工件表面粗糙度从0.25μm增大0.27μm,但仍可满足加工表面粗糙度要求,而砂轮修整量减少1/4,砂轮使用寿命延长;滚轮与砂轮的相对移动速度从0.1 mm/r增大到0.15 mm/r时,工件表面粗糙度值Ra从0.354μm上升到0.452μm,砂轮耐用度从750个工件降低到480个;修整速比增大,工件磨削表面粗糙度增大,当修整速比从0.61增大到1.35时,工件表面粗糙度值Ra从0.2μm增大到0.63μm。     

金刚石砂轮磨削铁氧体的表面粗糙度与形貌分析

本文研究了树脂结合剂金刚石砂轮磨削铁氧体材料时,磨削深度、工件进给速度对磨削表面粗糙度和材料去除方式的影响规律,以此探索提高铁氧体磨削表面质量的有效途径。采用单因素法设计试验方案对铁氧体进行磨削,测量表面粗糙度数据并对其进行方差分析,对铁氧体磨削表面形貌进行观察。结果表明：随着磨削深度、工件进给速度的增加,表面粗糙度值升高,同时表面塑性痕迹减少,脆性断裂痕迹增加,且磨削深度对表面粗糙度的影响要比工件进给速度的更显著,因此,制定磨削工艺时,考虑到粗磨为了提高效率,降低表面损伤,优化得到磨削工艺为磨削深度5μm,工件进给速度10 m/min;精磨为了获得较低的表面粗糙度,采用磨削深度5μm、工件进给速度为5 m/min,可以提高磨削表面延展性。     

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.     

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。     

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.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.