金刚石工具制造技术的发展与热点问题

文章就金刚石工具制造技术的发展历史,着重讨论了金刚石锯片的制造技术发展.并就金刚石表面镀覆、结合剂的预合金化和刀头制造技术等热点问题进行了较为深入的分析和具体技术介绍.在镀覆技术方面讨论了镀覆对金刚石工具质量的贡献和存在的问题及解决问题的方法;在结合剂的预合金化方面介绍了雾化法、共沉积法和机械合金化方法等,并对几种方法进行了比较,介绍了部分合金化粉末产品;在刀头制造技术方面介绍了金刚石有序排列、钎焊技术、轧制法制造刀头技术等.     

金刚石工具制造技术的发展与热点问题

文章就金刚石工具制造技术的发展历史,着重讨论了金刚石锯片的制造技术发展.并就金刚石表面镀覆、结合剂的预合金化和刀头制造技术等热点问题进行了较为深入的分析和具体技术介绍.在镀覆技术方面讨论了镀覆对金刚石工具质量的贡献和存在的问题及解决问题的方法;在结合剂的预合金化方面介绍了雾化法、共沉积法和机械合金化方法等,并对几种方法进行了比较,介绍了部分合金化粉末产品;在刀头制造技术方面介绍了金刚石有序排列、钎焊技术、轧制法制造刀头技术等.     

金刚石工具制造技术的发展与热点问题(上)

文章就金刚石工具制造技术的发展历史,着重讨论了金刚石锯片的制造技术发展.并就金刚石表面镀覆、结合剂的预合金化和刀头制造技术等热点问题进行了较为深入的分析和具体技术介绍.在镀覆技术方面讨论了镀覆对金刚石工具质量的贡献和存在的问题及解决问题的方法;在结合剂的预合金化方面介绍了雾化法、共沉积法和机械合金化方法等,并对几种方法进行了比较,介绍了部分合金化粉末产品;在刀头制造技术方面介绍了金刚石有序排列、钎焊技术、轧制法制造刀头技术等.     

激光焊接金刚石工具过渡层预合金粉末的试验研究

目前可以用于制备激光焊接金刚石工具过渡层粉末的方法主要有机械混合法、雾化法和化学共沉淀法。化学共沉淀法生产的粉末成分均匀,实现了粉末的预合金化,并且设备简单,生产成本低。此次试验采用草酸盐化学共沉淀法,成功制备了3种不同成分的激光焊接金刚石工具过渡层预合金粉末。焊接强度测试表明,3种粉末的焊接强度均满足欧盟EN13236安全标准,其中2#粉末的焊缝强度最高。X射线物相分析结果表明,3种粉末的主相都是Co3Fe7和CoFe。此外,固定Fe与Co的质量比,加入2wt.%的铜可以有效提高预合金粉末过渡层的焊接强度和稳定性。这是因为,Cu原子完全溶入到Co3Fe7或CoFe晶胞中并形成固溶体,产生了固溶强化。     

不断完善预合金粉末的性能,满足金刚石工具的应用(上)

随着预合金粉末在金刚石工具中使用量的增加,使用范围的不断扩大,不断完善预合金粉末的性能,进一步满足金刚石工具应用的需求,具有重大作用与意义。在预合金粉末生产方法中:湿法冶金方法生产的预合金粉,广泛并成功地应用在国外,但成本高,在国内市场应用较少。机械合金化方法多用于科研中,批量生产能耗大。在国内主要采用气雾化、水雾化、多金属化学共沉积法等生产预合金粉末。文章探讨了氧含量对金刚石工具性能的影响;介绍了国内不同生产设备条件下的还原工艺,进一步提出不断完善预合金粉性能的各种途径,以满足金刚石工具应用的需求。     

添加富铁预合金粉CSB-2的热压金刚石钻头胎体性能研究

Fe基胎体在金刚石钻头的领域中仍存在相当的潜力,粉末预合金化是现今金刚石工具制造的一个趋势。通过研究在980℃的烧结温度下不同含量的富铁预合金粉CSB-2的热压金刚石钻头胎体的力学性能及组织形貌表征,得到以下结论:CSB-2能提高胎体的力学性能,细化组织,使胎体更致密;富铁胎体在980℃的烧结温度条件下对金刚石存在着刻蚀作用,粉末预合金化能降低铁基胎体对金刚石的刻蚀,且使胎体对金刚石的润湿性增强,提高胎体对金刚石的包镶力。     

采用模板法制备毫米级半透明Al2O3空心球EI北大核心CSCD

以自制毫米级聚苯乙烯(PS)球为模板,采用物理包覆和真空烧结方法制备Al2O3半透明空心球。用离心加压物理包覆法制备PS–Al2O3复合球壳,经3步煅烧法制备出毫米级半透明氧化铝空心球。制备过程为:第1步以1℃/min的升温速率在320℃保温2 h和900℃保温2 h,去除模板得到白色氧化铝空心球素坯;第2步在1 300℃保温2 h,去除残余模板和大部分气孔,对氧化铝空心球壳预烧结;第3步在1 800℃真空条件下烧结,得到半透明氧化铝空心球,其球壳厚度约为150μm,具有较高的致密度,可用作惯性约束核聚变靶丸材料。     

碳化钨载铂的制备及其对硝基苯的电催化还原

以偏钨酸铵（AMT）为钨源前驱体,气流式喷雾干燥仪造粒,得到空心球状结构偏钨酸铵,固定床气固反应,以CO/CO₂为还原碳化气氛在800℃下制备了介孔空心球状碳化钨。采用氯铂酸作为铂源,用浸渍、气相还原法制备了Pt/WC粉末催化剂。通过XRD和SEM测试手段对Pt/WC粉末样品进行了表征,表明Pt成功负载在介孔WC材料上。采用循环伏安法、以Pt/WC粉末微电极为工作电极,研究了Pt/WC对在质子惰性介质中硝基苯的硝基还原的催化作用。结果表明,Pt/WC催化剂对硝基还原有着良好的电催化活性和化学稳定性。     

以空心球Fe2O3为铁源制备锂离子电池正极材料LiFePO4/C

以亚铁氰化钾,硫代硫酸铵等为反应物,CTAB作表面活性剂,采用水热法合成空心球Fe2O3。用X-射线粉末衍射,扫描电镜,高倍投射电镜对产物的组成,大小,形貌进行表征。结果表明,产物为纳米级空心球Fe2O3并以此空心球为原料成功合成锂离子电池正极材料LiFePO4/C。     

复合材料用预浸料

（续３）２．２．６粉末预浸法 粉末预浸法是制备热塑性树脂预浸料比较成功的方法,随着所用设备不同和工艺条件的差异,有多种方法。 ＢＡＳＦ结构材料公司开发了一种粉末浸渍工艺,具体过程未做任何透露。据称用其工艺制得的粉末预浸料,具有良好粘性和铺覆性,而且预浸料中不含溶剂,这就很容易制备外形复杂的构件,生产速度快,预浸料质量和最终产品的性能均得到提高,具有广泛使用前景。这种方法可以制备单向预浸带、织物预浸料、也可以预浸粗纱。 荷兰专利８６１０５１２５介绍了一种流态化床工艺,是将纤维束分散开来通过一个流态化…     

Microstructures and Properties of Plasma-Sprayed Segmented Thermal Barrier Coatings

Thermal barrier coatings (TBCs) with different levels of segmentation crack density were produced by spraying two types of ZrO₂–8Y₂O₃ powders. The fused and crushed powder has a greater capability of forming segmented coatings than the hollow sphere (HOSP) one. The highly segmented coatings reveal much lower porosity compared with traditionally sprayed coatings, thereby compromising the property of thermal insulation of TBCs. Microstructure and thermal conductivity of the HOSP coatings are more sensitive to the changes in spray conditions. Segmentation cracks had a strong influence in decreasing Young's modulus of coatings. Fifty hours heat treatment at 1250°C had little effect on the mechanical property of the highly segmented coatings.     

Preparation of nanometer AlN powders by combining spray pyrolysis with carbothermal reduction and nitridation

Nanometer AlN powders were prepared by combining spray pyrolysis with carbothermal reduction and nitridation (CRN). The aluminum oxide/carbon composite powders prepared by spray pyrolysis from a sucrose spray solution were several microns in size, with hollow and porous structures. Precursor powder with 67 wt% carbon content was transformed into phase-pure AlN powder by CRN at temperatures above 1,400 °C. The hollow-structured AlN powder was ground to 20 nm mean size by simple milling.     

Hollow Microsperes

Hollow microspheres are spherically symmetrical particles consisting of at least two phases. Their sales are continuously increasing because of a large number of well‐known and new applications. While most of the current needs for hollow microspheres are met by inorganic byproducts of combustion processes (cenospheres), the fabrication of tailor‐made hollow sphere structures by processes like spray‐drying as well as dripping, emulsion and suspension techniques is gaining more and more interest. Surface phenomena play an important role as far as formation, properties and stability of hollow microspheres are concerned. Template techniques can be used to yield structures that have not been available so far. Modeling and simulation of the formation processes are useful tools to understand the formation mechanisms and to simplify the scaleup.     

Sulfur/graphitic hollow carbon sphere nano-composite as a cathode material for high-power lithium-sulfur battery

The intrinsic low conductivity of sulfur which leads to a low performance at a high current rate is one of the most limiting factors for the commercialization of lithium-sulfur battery. Here, we present an easy and convenient method to synthesize a mono-dispersed hollow carbon sphere with a thin graphitic wall which can be utilized as a support with a good electrical conductivity for the preparation of sulfur/carbon nano-composite cathode. The hollow carbon sphere was prepared from the pyrolysis of the homogenous mixture of the mono-dispersed spherical silica and Fe-phthalocyanine powder in elevated temperature. The composite cathode was manufactured by infiltrating sulfur melt into the inner side of the graphitic wall. The electrochemical cycling shows a capacity of 425 mAh g⁻¹ at 3 C current rate which is more than five times larger than that for the sulfur/carbon black nano-composite prepared by simple ball milling.     

聚丙烯/硅－铝空心球增强材料的力学性能

用刚性无机粒子硅-铝（Si-Al）空心球填充增强聚丙烯,研究了Si-Al空心球的含量、粒径及偶联剂对PP/Si-Al空心球增强材料力学性能的影响,结果表明,填充40%以下的Si-Al空心球的增强PP的缺口冲击强度、拉伸强度、拉伸弹性模量、弯曲强度和弯曲弹性模量均显著提高;Si-Al空心球为20%时,增强PP的冲击强度达到最大值,与填充粒径10μmSi-Al空心球相比,填充粒径5μmSi-Al空心球的增强PP的缺口冲击强度和拉伸弹性模量高。填充经偶联剂A和C表面处理的Si-Al空心球有利于提高增强PP的缺口冲击强度、弯曲强度及弯曲弹性模量。填充刚性无机粒子Si-Al空心球不仅能提高PP的力学性能,而且能降低PP的成本,为Si-Al空心球的应用开辟了新途径。     

A new Al2O3 porous ceramic prepared by addition of hollow spheres

A method for making porous ceramic prepared by adding hollow spheres was developed, and the resulting porous ceramic was named as hollow spheres ceramic. Water soluble epoxy resin was used as a gel former in the gelcasting process of the Al₂O₃ hollow sphere and Al₂O₃ powder, the porous ceramic porosity varies from 22.3 to 60.1 %. The influence of amount of Al₂O₃ hollow sphere and sintering temperature on the microstructure, compressive strength and thermal conductivity were investigated. With an increasing amount of hollow sphere in the matrix, the porosity increases, which leads to decreased bulk density, compressive strength and thermal conductivity. The compressive strength of the porous ceramics has a power law relation with the porosity, and the calculated power law index is 4.5. The equations of the relationship between porosity and thermal conductivity of porous ceramics are proposed. The thermal conductivity of samples with 60.1 % porosity is as low as 2.1 W/m k at room temperature.     

油页岩灰渣制备空心陶瓷微球及机理探讨

以油页岩灰渣为实验原料,利用火焰喷枪熔射法制备了空心陶瓷微球.采用TG-DSC对油页岩灰渣进行热分析,采用SEM和XRD分别对油页岩灰渣和空心陶瓷微球的微观形貌和物相组成进行分析.研究结果表明,利用火焰喷枪熔射法制备的微球绝大多数为球状,极少部分为不规则形状,微球破碎后可发现其为空心结构;空心微球的形成机理为:油页岩灰渣粉末受热熔化、发气物质形成气泡、气泡合并、降温凝固、最终形成空心微球;油页岩灰渣自身疏松的结构、所含充足的发气物质和适宜的熔射温度是形成微球空心结构的重要因素.     

CTAB含量对介孔空心微球结构的影响

介孔空心微球具有大的空心腔体和壳体上小的介孔结构,使得介孔空心微球结构材料作为一种新型功能材料有着广阔的应用前景。本文使用喷雾干燥法合成介孔空心微球,以CTAB作为致孔剂,TEOS作为硅源,系统研究了不同CTAB含量下产物的结构,发现n（CTAB）/n（TEOS）=0.2时,产物颗粒具有较好的空心结构,颗粒外壳上的介孔有序度高,当n（CTAB）/n（TEOS）的值增加时,产物中的空心颗粒含量减小,而且壳上的介孔的有序度下降,介孔孔壁厚度也减小。     

不球磨无机粉体发光材料制备技术进展

综述了不球磨无机粉体发光材料制备技术进展,着重总结了稀土掺杂型无机粉体发光材料的制备方法。介绍了溶胶-凝胶法,燃烧合成法,微波合成法,共沉淀法,喷雾热解法,水热合成法,气相反应合成法和微乳液法等制备方法。对比总结了每种合成方法的优缺点,并对其未来发展趋势作了展望。综述国内外研究报告和论文82篇。     

Mikrohohlkugeln

Micro Hollow Spheres Micro hollow spheres are spherically symmetrical particles consisting of at least two phases. Their sales are continuously increasing because of a large number of potential applications that have been well known since long. While most of the current needs for micro hollow spheres are met by inorganic by‐products of combustion processes (cenospheres), the preparation of tailor‐made hollow sphere structures is mainly determined by processes like spray‐drying as well as dripping, emulsion and suspension techniques. Surface phenomena play an important role as far as formation, properties and stabilities of micro hollow spheres are concerned. Template techniques can be used to yield structures that have not been available so far. Modeling and simulation of the formation processes are useful tools to understand the formation mechanisms and to simplify the scale‐up.