热压金刚石钻头铁基胎体机械性能的研究

为了系统研究铁基金刚石钻头胎体配方组成对胎体机械性能的影响规律,本文采用极端顶点法设计胎体配方试验。胎体配方组成为Fe（含P23%）、WC、663-Cu、Ni、Co和Mn粉,试验测试指标为胎体硬度和耐磨性。对测试结果进行回归分析和非线性规划求解,分析了胎体配方组成对胎体机械性能的影响规律,从理论上得出了胎体硬度和耐磨性的最优值以及相应的胎体配方。结果表明：P可降低铁基胎体的烧结温度,有效阻止Fe对金刚石的热侵蚀作用。随着Fe（P-Fe）和WC含量的增加,胎体的硬度和耐磨性都得到明显改善,铁基胎体可以满足热压金刚石钻头对其机械性能的要求。     

金刚石圆锯片用铁基结合剂的研究

利用抗弯强度试验和扫描电镜对Fe基结合剂的力学性能和显微组织进行了较详细的研究，提出了改善铁基结合制性能的方法。实验结果表明：含Fe量大于40％的结合剂对烧结温度很敏感，极易火烧及过度浸蚀金刚石。采用金刚石表面镀Ni－Co－W－P或将Fe－Ni－Cu－C部分预合金化并加少量Co的办法可有效提高结合剂对金刚石的把持力，减少Fe对金刚石的浸蚀。部分预合金化并加入少量Co的办法还可以提高结合剂的合金化程度，显著改善胎体的力学性能。     

Fe70Ni30合金粉体触媒及合成金刚石中杂质元素的原子发射光谱分析

为了分析合成金刚石中的杂质元素,以粉体Fe70Ni30合金触媒及石墨为原料,用静态高压技术合成出金刚石,分别对触媒和金刚石进行了原子发射光谱分析.测试结果表明:触媒里具有Co、Ca和Mn等22种含量值在0.0001～1.5 wt %之间的杂质元素;合成金刚石中有含量值在0.00005 ～ 0.02 wt %之间的Fe、Ni和Ca等10种杂质元素.这些杂质元素对金刚石质量和性能的影响进行了定性讨论.采用粉末触媒合成金刚石,其合成晶体中含有一定量的杂质元素是很难避免的,除合理采用合成工艺外,还可以通过严格控制原材料纯度等一些措?来降低合成晶体中杂质元素的含量,进而提高合成金刚石的质量.     

镀膜金刚石对刀头性能的影响及其机理研究

将镀有金刚膜的金刚石应用于Cu,Fe,Ni和Co基胎体材料中经热压制得试样，发现用镀有金属膜石制得的试样的磨削性能不同程度地优于未镀金属膜的金刚石制得的试样，通常热压过程中金刚石镀膜一方面提高金刚石胎体间的界面粘线强度，一方面防止金刚石在热压时的高温损伤，其中后作用比前更显。实验中还发现，镀膜金刚尤其适用于Fe基胎体材料的金刚石工具。     

掺杂Fe基非晶合金调控Ni-金刚石/Al复合材料的导热性能

通过对金刚石表面化学镀Ni对金刚石颗粒镀覆金属层进行表面改性.采用X射线衍射仪(XRD)对Fe基非晶合金进行物相分析,利用差示扫描量热仪(DSC)测试Fe基非晶粉的特征温度点,采用扫描电子显微镜(SEM)观察界面结合情况和界面产物微观形貌,用能谱仪(EDS)进行物质元素分析,采用激光热导仪(LFA447)对复合材料进行...     

W基胎体金刚石钻头的初步研究

通过试验研究,在普通热压烧结条件下,利用可降低烧结温度和压力的活化元素,并采用相应的烧结工艺制造的W基胎体金刚石钻头,在坚硬、致密、弱研磨性岩层中能持续高效钻进,并有较长的寿命。     

高温钎焊过程中Ni-Cr合金对金刚石磨粒静压强度的影响

采用C类(Ni82Cr7Si4.5B3.1Fe3)和E类(BNi76Cr15P9)两种钎料对金刚石进行真空炉中钎焊。通过静压强度测试对各种状态下的金刚石钎焊性能进行评价,并借助SEM以及拉曼光谱仪对金刚石表面碳化物的形貌和金刚石的石墨化进行检测分析。结果表明:钎焊高温对金刚石强度的影响较合金钎料的化学侵蚀作用而言小很多;触媒元素Ni、Fe和强碳化物形成元素Cr等引起的化学侵蚀,是导致金刚石静压强度降低的两个主要原因;不同品质的金刚石经过高温钎焊后,静压强度值出现不同程度的降低。     

(Ti,W)C固溶体基金属陶瓷的研究进展

本文概括了(Ti,W)C固溶体基金属陶瓷的性能及优势,分析了(Ti,W)C固溶体粉末的制备方法如碳热还原法、燃烧合成法(自蔓延高温合成法)、机械合金化和机械诱发自蔓延反应;讨论了已经应用的(Ti,W)C基金属陶瓷的烧结方法如真空烧结,自蔓延高温合成,高频诱导加热合成和放电等离子体烧结等方法,并指出有可能应用的其它烧结方法如微波烧结、选择性激光烧结、二阶段烧结、等离子体活化烧结等方法;系统地综述了不同成分粘结剂(Ni、Co/Ni、Fe、Fe Al、NiAl_3)、第二类碳化物(Mo_2C、WC)和组元含量(C、Mo、W、W与Ti的量之比)以及粉末状态(纳米粉末或固溶体形状)对(Ti,W)C基金属陶瓷组织和性能的影响,最后对(Ti,W)C基金属陶瓷未来的研究进行了展望。     

烧结压力对低液相Fe基预合金钻头胎体性能的影响

在烧结温度为950℃、保温时间为5 min及不同烧结压力条件下开展热压烧结试验，对比研究烧结压力对3种低液相Fe基预合金钻头胎体和1种传统Fe基钻头胎体性能的影响，具体包括胎体压入硬度、抗弯强度、致密度和金刚石包镶强度等力学性能，以及金刚石的热损伤情况和钻头胎体的微观组织结构与形貌特征等。结果表明：随着烧结压力增大，低液相空白胎体的压入硬度、抗弯强度和致密度逐渐增大，而传统Fe基空白胎体的压入硬度和抗弯强度呈现先增大后减小的趋势，其致密度为增大趋势；对于含金刚石的胎体，低液相与传统Fe基胎体抗弯强度均随烧结压力增大而增大，当烧结压力为20 MPa时，继续增大压力，低液相含金刚石胎体的抗弯强度趋于稳定，而传统Fe基含金刚石胎体的抗弯强度略有下降。同时，随着烧结压力的增大，低液相胎体的均一性明显增强，但金刚石的热损伤加剧。综合胎体的力学性能与断口形貌特征，优选的烧结压力为20 MPa，此时的低液相Fe基预合金胎体硬度、抗弯强度可满足孕镶金刚石钻头需要。     

Fe-Co-Ni-Zr-Mo-W-B块体非晶合金的玻璃形成能力与热稳定性

采用铜模铸造法,可以制备出直径为3 mm的非晶圆柱棒.结合差热分析、X射线衍射和透射电镜分析测试结果,从动力学和结构学等方面阐述了Ni元素对Fe58Co10-xNixZr10Mo5W2B15(x=0,3,4,5,6,摩尔分数,%)合金系玻璃形成能力和热稳定性的影响.结果表明:Ni元素含量的微量变化可以明显改善Fe58Co10-xNixZr10Mo5W2B15(x=0,3,4,5,6)合金系的玻璃形成能力;当Ni含量达到4%时,Fe58Co6Ni4Zr10Mo5W2B15具有最佳的玻璃形成能力,晶化温度(Tx)、玻璃转变温度(Tg)、过冷液相区宽度(△Tx)、玻璃形成能力判据Trg和y分别为887 K、957 K、70 K、0.590 2和0.400 4.     

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.     

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.     

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.     

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.