Ce-Mn合金低温抛光CVD金刚石厚膜

研究开发了一种低温、快速抛光化学气相沉积(CVD)金刚石厚膜的新技术,该技术是利用金刚石(C)和溶碳活性很高的稀土金属铈(Ce)和过渡金属锰(Mn)所熔炼出的Ce-Mn合金之间的热化学反应,在一定的工艺条件下对金刚石厚膜进行有效的抛光.详细讨论了合金组成对抛光速率和表面粗糙度(Ra)的影响,并且用扫描电镜和拉曼光谱对抛光后的膜表面进行了表征.结果表明:Mn含量较低的合金从抛光率上和抛光效果上考虑都更有利于获得良好抛光的金刚石厚膜,Ce-3%Mn原子比组成的合金,在660℃、抛光2 h的实验条件下,使膜的粗糙度由10.8490 μm降低到3.6826 μm,抛光速率达到37.5 μm/h.适量Mn的加入在降低抛光温度的同时仍然可以保证良好的抛光效果,优化了热化学抛光的工艺,而且该抛光技术不会破坏金刚石厚膜质量.     

部分熔融Ce-Fe合金低温快速抛光CVD金刚石膜

采用溶碳活性很高的稀土金属Ce和过渡金属Fe熔炼出Ce-7％Fe（原子分数，下同）合金，利用该合金对CVD金刚石膜进行热化学抛光。结果表明：Ce-7％Fe合金在592℃就可以抛光金刚石膜，比报道的稀土抛光温度要低200℃以上；在680℃抛光3h表面粗糙度Ra值由原来的5．95μm降低到0．69μm，抛光效率高达30μm／h；SEM观察表明，抛光使膜的表面光洁度有明显提高；经拉曼光谱检测，抛光没有对金刚石膜造成任何污染。     

稀土金属Ce抛光CVD金刚石膜的研究

研究了一种快速有效地抛光CVD金刚石厚膜的技术.该技术是利用化学活性很强的稀土金属铈(Ce)与金刚石(碳)的固相化学反应,在一定的工艺条件下对金刚石膜进行的快速有效的抛光.讨论了金刚石膜抛光效果的影响因素及初步探讨了固态稀土Ce抛光金刚石膜的抛光机理.此外,还对抛光前后的金刚石膜以及反应产物进行了Raman光谱和X射线衍射谱(XRD)分析,从而初步得到了该方法抛光金刚石的抛光机理.研究表明抛光速率和质量与抛光温度、时间和加载的压力有关;在680℃抛光2h就已出现抛光效果;经过700℃,2h,加载为1N抛光条件的处理后表面粗糙度(Ra)由原来的5.9762μm降低到2.0247μm;在750℃时获得了较高的抛光率,约35μm/h.     

金属粉末增强机械抛光单晶金刚石

目的 研究具有催化活性的镍、钴金属粉末对单晶金刚石机械抛光的影响,以期获得低成本高效率的单晶金刚石抛光工艺。方法 以高温高压法（HPHT）制备的Ⅱa型单晶金刚石为样品,采用机械抛光的方法沿单晶金刚石（100）晶面的[100]晶向进行抛光,抛光介质分别为金刚石研磨膏、金刚石微粉、金刚石微粉与镍粉混合粉末、金刚石微粉与钴粉混合粉末。样品表面粗糙度通过原子力显微镜（AFM）进行测定,通过扫描电镜（SEM）及能谱仪（EDS）对样品表面形貌及元素成分进行分析表征。结果 金刚石微粉作研磨粉时,抛光速率最高,达到900 μm/h,但表面粗糙度相对较差,为4.15 nm;镍粉或钴粉与金刚石微粉的混合粉末作抛光介质时,可以实现单晶金刚石的高效抛光,其中以钴粉与金刚石微粉的混合粉末作为抛光介质时的抛光效果最佳,抛光速率为875 μm/h时,表面粗糙度为1.52 nm。结论 镍、钴金属粉末与金刚石微粉混合作为抛光粉料,可以实现单晶金刚石的高效率、高质量抛光。     

用于金刚石摩擦化学抛光的Ni-W合金盘制备

为探究镀液成分、工艺条件等因素对Ni-W合金镀层的影响,制备出低内应力、高硬度的Ni-W合金盘,用于金刚石的摩擦化学抛光。采用单一性实验分别探究络合剂浓度、溶液pH、糖精钠浓度对镀层内应力、钨含量、硬度以及沉积速率的影响,并探究不同添加剂对镀层表面整平的效果。最终选用水杨醛为整平剂,并采用反向脉冲电流降低了镀层表面粗糙度,制备出硬度达HV 713,镀层厚度约为0.66 mm的Ni-W合金盘。使用合金盘对金刚石进行摩擦化学抛光,并探究合适的抛光工艺参数。在合金盘转速为8 000 r/min,压力为40 N时,金刚石的抛光效果较好,其材料去除率为5.56μm/min,磨削比达0.394,金刚石表面粗糙度S_a为3.7 nm。使用传统铸铁盘对金刚石进行摩擦化学抛光,通过对比磨损参数发现,Ni-W合金盘能够达到更好的抛光效果。     

单晶蓝宝石高效超精密加工技术研究

针对光电子器件、集成电路等应用领域对单晶蓝宝石高质量的表面需求,而单晶蓝宝石自身的硬度和良好的化学稳定性给抛光带来较大的困难。文章在分析、对比直接采用2μm金刚石磨料化学机械抛光蓝宝石基片效果的基础上,提出机械研磨与化学机械抛光相结合的工艺抛光蓝宝石。结果表明,采用10μm的碳化硼磨料机械研磨蓝宝石,材料去除率为8.03μm/h,表面粗糙度Ra由1.18μm迅速降至22.326 nm;采用粒径为2μm和0.5μm的金刚石磨料化学机械抛光蓝宝石晶片,有效的去除机械抛光带来的损伤,最后表面粗糙度Ra可达0.55 nm。此抛光工艺能满足蓝宝石晶体高效、超光滑、低损伤的抛光要求。     

CVD金刚石厚膜的机械抛光研究

化学气相沉积(CVD)制备的金刚石膜表面粗糙且厚薄不均匀,在许多情况下不能直接使用,必须对其进行抛光.本文研究了不同型号的金刚石微粉对CVD金刚石厚膜研磨的影响,通过对研磨结果的比较分析,优化出一种高质量高效率的抛光方法,即先采用W40和W28金刚石微粉,分别研磨2 h,然后用W0.5金刚石微粉研磨4 h.经扫描电子显微镜(SEM)和原子力显微镜(AFM)测试分析表明:金刚石膜的平均去除率为12.2 μm/h,粗糙度Ra由4.60 μm降至3.06 nm,说明该抛光方法能实现金刚石膜高质量、高效率的抛光.     

CN200710053047．4金刚石膜的抛光方法

本发明涉及一种金刚石膜的抛光方法。金刚石膜的抛光方法，其特征在于它包括如下步骤：1）首先在金刚石膜表面镀涂能够与碳形成强碳化物的纯金属或合金；2）在真空炉中加热，真空度10^-1-10^-4Pa，加热温度大于800℃，时间5～30分钟，在表面形成碳化物层，厚度为0．05～0．5μm；3）在机械抛光机上，采用硬度比金刚石低的SiC或Al2O3作为磨料，对步骤2）所得的金刚石膜进行抛光，时间5～30分钟；     

钴铬钼合金磁流变抛光工艺研究

目的 去除难加工材料钴铬钼合金车削后形成的规则性螺旋刀痕并获得超光滑表面。方法 采用磁流变抛光方法,对车削后的钴铬钼合金表面进行抛光加工。研究了磁体排布方式、加工间隙、抛光装置、转速和磨料粒径等工艺参数对钴铬钼合金表面形貌和表面粗糙度的影响规律,寻找获得超光滑表面的工艺参数组合,并对抛光后的钴铬钼合金表面使用表面轮廓仪进行测量。结果 钴铬钼合金表面形貌受各方面因素的综合影响,双磁体异向排布的磁通密度向工件集中,使得磁性羰基铁颗粒与金刚石磨料在抛光过程中结合力更强,增大了有效工作区域;表面粗糙度随着加工间隙的增加(从1 mm增大到4 mm)先减小后增大,在2 mm时得到优化的加工效果;表面粗糙度随着抛光装置转速的增加(从400 r.min^–1增大到1 000 r.min^–1)先减小后增大,在600 r.min^–1时得到优化的加工效果;相比于0.5、1.5、2.5 µm粒径的金刚石磨料,使用2 µm的金刚石磨料进行抛光时表面粗糙度最小。当使用双磁体异向排布,在工作间隙为2 mm、抛光装置转速为600 r.min^–1、金刚石磨料粒径为2 μm的工艺参数组合下对钴铬钼合金采用磁流变抛光加工120 min时,其表面粗糙度从初始的640 nm 降低至5 nm。结论 应用磁流变抛光方法抛光钴铬钼合金可以得到超光滑表面。     

Si3N4工程陶瓷基底金刚石涂层生长规律及性能

为了避免氮化硅材料因产生裂纹或延伸破裂等造成的失效,利用热丝化学气相沉积法（Hot filament chemical vapor deposition,HFCVD）在氮化硅基底上沉积具有高硬度的金刚石涂层,采用单因素影响试验,分别探究碳源浓度、腔室压力、基底温度对金刚石成膜过程的影响机制,探究微米和纳米金刚石涂层的最优生长工艺参数。利用拉曼光谱仪（Raman）、X射线衍射仪（XRD）、扫描电子显微镜（SEM）和原子力显微镜（AFM）对不同参数制备出的金刚石的形核、表面形貌、薄膜质量、表面粗糙度等进行表征,利用洛氏硬度计分析膜基结合力。结果表明,腔室压力越大,活性物质到达基底的动能越小,不利于金刚石的成核和生长。生长速率和表面粗糙度主要受甲烷浓度的影响：甲烷浓度从1%到7%,生长速率从0.84μm/h上升到1.32μm/h;表面粗糙度Ra从53.4 nm降低到23.5 nm;甲烷浓度过高导致涂层脱落严重,膜基结合力变差;晶面形貌和金刚石含量受到基底温度的影响较为明显,随着温度升高,金刚石质量提高。综合基底温度、腔室压力对金刚石涂层的影响,确定最佳生长温度为900℃,气压为1 k Pa。...     

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.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

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.