航空摩擦材料混料时间研究

研究了某特定航空摩擦材料混料时间对混合料松装密度和颗粒形貌以及对烧结材料硬度、摩擦磨损性能和微观组织的影响。在特定配料条件下 ,结果表明 ,混料过程使聚集的颗粒分散 ,表面光滑 ,并有割断或磨碎原始颗粒的作用。随着混料时间的增加 ,烧结摩擦材料的硬度降低、摩擦系数增加、材料的磨损量增加 ,而对偶材料的磨损量下降。混料时间为 0～ 8h时 ,混合料松装密度和烧结材料的组织均匀性随混料时间的增加而增加 ,随后不再增加。对所选择的摩擦材料 ,混料 8h可以获得均匀的混合料和组织均匀的烧结材料 ,混合料的松装密度为 1 6 3g/cm3;混料 6～ 10h时 ,烧结材料具有良好的摩擦磨损性能 ,其摩擦系数为 0 192～0 2 0 5 ,总磨损量 (材料磨损 +对偶磨损 )为 3 78～ 3 90 μm/次 ,使用后期无材料崩块现象 ,材料的烧结硬度为 6 2 5～ 6 6 8HRF。     

放电等离子烧结TbFeCo磁光靶材工艺研究

研究了采用放电等离子烧结技术制备TbFeCo磁光靶材的工艺过程，考察了烧结温度对材料组织均匀性和致密度的影响。利用扫描电子显微镜和能谱分析仪对材料的微观组织形貌及成分进行了分析，同时用阿基米德法测量了材料的密度。结果表明：适当的提高烧结温度可以使材料得到均匀的组织，理想的致密度。但过高的烧结温度会造成材料局部组织的熔化，使材料的组织均匀性变差，l010℃的烧结温度是制备具有均匀组织和理想致密度Tb(Fe，Co)3材料的最佳温度。     

W-Ni-Sr电极烧蚀形貌研究

制备了W-Ni-Sr钨合金电极材料, 分析了W-Ni-Sr电极烧蚀失效后的形貌, 并探讨了钨合金电极材料的优化方向。结果表明, 电极的击穿和烧蚀主要发生在钨酸盐相, 烧蚀后仅发生Ni₁₇W₃和Sr₃WO₆两相的消耗, 没有新相产生; 主要是低熔点组分发生熔化、溅射, 沉积在电极表面, 导致电极表面形貌改变, 从而影响发射均匀性; 改善材料的组织均匀性和减小晶粒度可有利于钨合金电极使用性能的提高。     

外科植入物用Ti-6A1—7Nb合金板棒丝材制备及性能表征

在工业生产条件下,通过熔炼、锻造和轧制工艺制备出不同规格的外科植入物用的Ti-6A1-7Nb合金板、棒、丝材,表征了不同规格材料的组织与性能,进行了Ti-6A1—7Nb合金材料体外细胞毒性试验、刺激与迟发型超敏反应试验、污染物致突变性检测和骨植入试验。研究结果表明：板、棒、丝材组织与性能均满足GB23102-2008、GB／T13810-2007和ASTMF1295标准要求;Ti-6A1—7Nb合金材料不含毒性组元,生物相容性好,是一种比Ti-6A1-4V合金更理想的外科植入物材料;多种形式植入件的近百例临床使用效果良好,适合临床应用。     

喷射成形70Si30Al合金封装材料的组织性能研究

利用喷射成形技术制备了70Si30Al合金新型电子封装材料,研究了材料沉积态、热压态的显微组织演变规律,测试了材料的各项性能。结果表明:沉积态材料显微组织细小均匀,一次Si相尺寸大约在10-40μm左右,且均匀弥散分布。经过热压后,材料的热膨胀系数为7×10-6-9×10-6K-1,热导率可以达到120 W.m-1.K-1。     

电子束选区熔化成形方向选择对TC4合金性能的影响

采用电子束选区熔化针对不同成形方向进行打印,利用扫描电子显微镜(SEM)和金相显微镜(OM)研究了电子束选区熔化成形Ti-6Al-4V合金的组织特征,获得了成形后Ti-6Al-4V合金力学性能,揭示了成形方向选择对力学性能的影响规律。结果表明:横向打印产品材料抗拉强度能够达到986 MPa、屈服强度能够到达880 MPa、延伸率能够到达11.2%,明显优于纵向打印产品材料的性能;横向打印材料在打印过程中冷却速度较快,β相先转化成α′马氏体,最后分解为α+β相组成的网篮组织;纵向打印材料在打印过程中材料被反复加热,最终形成魏氏组织(过热组织)。     

熔渗铜对高合金烧结钢组织的影响

研究了熔渗铜对Fe-Cu-5X(Ni、Mo、Cr、W）－C合金组织的影响。实验表明：熔渗铜不仅可以提高材料的密度,而且可以改善材料的组织均匀性,提高材料的合金化程度。     

β热处理对SEBM Ti-6Al-4V Diamond点阵材料显微组织和力学性能的影响

采用电子束选区熔化(SEBM)技术制备Ti-6Al-4V Diamond点阵材料,研究β热处理(1100℃/2 h/FC)对其显微组织与力学性能的影响。结果表明,经β热处理后,Ti-6Al-4V Diamond点阵材料的显微组织由原始β柱状晶转变为等轴晶,针状马氏体α′相以及α+β细片层组织转变为相互平行的α+β粗片层组织,且α片层平均厚度由0.8μm增加至7.4μm。此外,Ti-6Al-4V Diamond压缩应变增加,最大可达13.1%,但强度降低;热处理对点阵材料的模量影响较小。点阵材料的结构与材料具有独立性,热处理不会改变Ti-6Al-4V Diamond点阵材料强度、模量与相对密度的指数关系。     

SrCO_3添加量对钨合金电极材料组织和性能的影响

本文分析了SrCO_3添加量(质量分数)对钨合金电极材料组织、密度、硬度、电导率、热导率的影响。结果表明:SrCO_3质量分数在3%~7%范围内对电极材料的组织均匀性影响不大;SrCO_3质量分数为10%时,材料中部分区域出现了Sr_3WO_6的聚集,呈现出明显的组织不均。电极材料的相对密度随SrCO_3质量分数增加缓慢降低,当SrCO_3质量分数达到10%时,降低幅度加大。电极材料的硬度、电导率、热导率等性能随SrCO_3质量分数增大而降低,当SrCO_3质量分数达到10%时降低幅度加大,与相对密度随SrCO_3质量分数增大而变化的趋势一致。在本文研究范围内,SrCO_3最佳添加量(质量分数)为7%。     

锻造对飞机刹车副动片钢对偶材料摩擦性能与组织的影响

研究了锻造对飞机刹车副动片钢对偶材料摩擦磨损性能与组织的影响,结果表明:锻造提高了动片钢对偶材料的耐磨性和抗收缩性。     

Influence of Functionally Graded Material on Buckling of Skew Plates under Mechanical Loads

In this technical note, the critical buckling of simply supported functionally graded skew plate subjected to mechanical compressive loads is evaluated using first-order shear deformation theory in conjunction with the finite element approach. The material properties are assumed to vary in the thickness direction according to the power-law distribution in terms of volume fractions of the constituents. The effective material properties are estimated from the volume fractions and the properties of the constituents using the Mori–Tanaka homogenization method. The effects of aspect ratio, material gradient index, and skew angle on the critical buckling loads of functionally graded material plates are highlighted.     

酒钢7号高炉机械探尺不探料面原因探索

本文针对炼铁厂7号高炉机械探尺长期存在的不跟料面情况进行介绍,系统性地介绍了一种解决机械探尺不探料面问题的分析方法。文章运用受力分析方法,肯定了探尺运行中存在卡阻问题,再从电气、机械、环境三个方面查找卡阻原因,最终通过探尺解体检修,验证了理论分析的正确性。     

Mechanical properties of a metallic composite material based on an aluminum alloy reinforced by dispersed silicon carbide particles

The mechanical properties of a composite material with a matrix of aluminum alloy D16 reinforced with dispersed silicon carbide particles have been studied. The physicomechanical properties (density, elastic modulus, ultimate tensile strength, and limiting strains) of the composite material with various filler contents are determined experimentally. The experimental results are compared to the results of a theoretical simulation obtained using elastic and elastoplastic models of the composite material. The experimental and the calculated mechanical properties of the composite material with the volume content of the filler up to 30% agree well with each other.     

Structural changes in VT1-0 titanium induced by deformation during explosion welding

The hardening of VT1-0 titanium is studied during the formation of a multilayer material by explosion welding. The structural transformations in titanium plates are analyzed by metallographic and electron-microscopic methods. The mechanical properties of the welded multilayer titanium stacks are estimated using static and dynamic mechanical tests.     

Effect of the Cryogenic Treatment on Polyamide and Optimization of Its Parameters for the Enhancement of Wear Performance

Polyamide (PA) is generally used in automotive applications in which the extensive mechanistic situations lead the material to wear. To deal with this situation, attempts are made to treat this material cryogenically using liquid nitrogen. The material is treated at different temperatures (?80, ?140 and ?185?°C) for stipulated time period (4, 8, 12, 16, 20 and 24?h) in the cryostat. Cryo-treated samples are then allowed to attain the ambient temperature and tested for studying the effect of cryogenic treatment. Selected material is also studied simultaneously for thermal ageing. The mechanical, thermal and structural properties of ??un-treated?? and ??cryo-treated?? PA are studied in a comparative manner. Mechanical properties like wear performance and tensile properties are evaluated. The morphological changes due to cryo-treatment are investigated using scanning electron microscopy. Structural characterization by X-ray diffraction and Fourier transform infrared spectroscopy revealed the change in % crystallinity, which is found to be the most important parameter responsible for enhancement of wear performance. In a similar way, thermal changes are also studied by using differential scanning calorimeter. Experimental data is evaluated for the polymer with improved structural, mechanical and thermal properties in order to get optimized parameters for the cryo-treatment.     

Preparation of TiAl15Si15 intermetallic alloy by mechanical alloying and the spark plasma sintering method

This work is devoted to the preparation of alloys based on intermetallic compounds in the Ti–Al–Si system by powder metallurgy using mechanical alloying and the spark plasma sintering (SPS) method. The aim was to describe the formation of intermetallic phases during mechanical alloying of TiAl15Si15 (wt-%) alloy and to consolidate the powder prepared by optimised conditions. Phase composition, microstructure and hardness of compacted alloy were determined. Four hours of mechanical alloying is sufficient time for preparation of pure elements free material composed only of intermetallic phases. After consolidation, the TiAl15Si15 alloy has a homogeneous structure composed of silicide (Ti₅Si₃) in aluminide (TiAl) matrix. The hardness of the material reaches 865?±?42 HV 5.     

Material Characterization of Austempered Ductile Iron (ADI) Produced by a Sustainable Continuous Casting–Heat Treatment Process

Selecting a suitable manufacturing process is one way of achieving sustainability of a product by diminishing energy consumption during its production cycle and improving material efficiency. The article attempts to explore the new processing technology for direct manufacturing of lightweight austempered ductile iron (ADI) casting in a permanent mold. The new processing technology is based on the innovative integrated approach toward casting and heat-treatment process. In this technology, the ductile iron samples obtained using the permanent mold are first austenized immediately after solidification process followed by austempering heat treatment in the fluidized bed and then air cooled at room temperature to obtain ADI material. The influence of austempering time on the microstructural characteristics, mechanical properties, and strain-hardening behavior of ADI was studied. Optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses were performed to correlate the mechanical properties with microstructural characteristics. It was observed that the mechanical properties of resulting ADI samples were influenced by the microstructural transformations and varied retained austenite volume fractions obtained due to different austempering time. The results indicate that the strain-hardening behavior of the ADI material is influenced by the carbon content of retained austenite.     

Acoustic Determination of Properties Possessed by Porous Titanium

Powder Metallurgy and Metal Ceramics - To impart the optimal structure to a powder material and promote high mechanical properties, the production process is to be monitored at each step using...     

机械球磨技术在材料制备中的应用

综述了机械合金化、机械研磨以及机械涂覆三种机械球磨技术在材料制备领域中的应用和作用机理,讨论了三种机械球磨技术在材料制备中的优势与弊端,展望了该技术的今后发展方向。     

Comparison of the Wear Properties of Polymer Composites Having CNT With and Without Glass Fiber Reinforcement

The adoption of light weight and high performance polymer matrix composites are needed for industries related to aerospace, automotive, consumer goods, etc. Polymer fiber reinforced composite material have very good desirable mechanical and thermal properties like low density, higher specific stiffness with high specific strength and a controlled co-efficient of thermal expansion with dimensional stability. The addition of carbon nanoparticle in these composites improved mechanical as well as wear properties of the material, which leads to more applications of these composites in various fields. In the present investigation carbon nanotube addition along with the glass fiber reinforced composite material was used as work material. The sliding wear tests were carried out on pin on disc wear tester. The tribological performance was studied by varying the applied load. The wear surfaces were analyzed by using scanning electron microscope, X-ray diffraction and energy-dispersive X-ray spectroscopy which are presented in detail.