机械活化-放电等离子烧结制备Y3Al5O12陶瓷

以高纯Y2O3和Al2O3粉体为原料,通过机械活化和放电等离子烧结制备Y3Al5O12(YAG)陶瓷.研究结果表明:机械活化Y2O3和Al2O3粉体,不但细化了Al2O3颗粒,而且使Y2O3发生了晶态转变,由立方晶转变为斜方晶,并最终非晶化;机械活化过程最终还合成了过渡产物YAlO3(YAP),但球磨5h后,继续延长球磨时间,会引入大量ZrO2杂质;球磨处理的Y2O3和Al2O3粉体具有很高的活性,能促进在较低温度下通过放电等离子烧结合成YAG.对球磨5h的粉体在不同温度进行放电等离子烧结的研究表明,在1000℃可获得纯YAG陶瓷,在1 400℃可得到相对密度为99.4%、晶粒大小为1～2μm的YAG陶瓷.     

工艺参数对Fe3Al/Al2O3复合材料力学性能的影响研究

以自制的亚微米Fe3Al为增强相、Al2O3为基体相,通过常压烧结制备出Fe3Al/Al2O3复合材料,研究了Fe3Al含量、烧结温度及保温时间对复合材料力学性能的影响.结果表明:增加Fe3Al含量、提高烧结温度及延长保温时间都可以不同程度的提高复合材料力学性能.最佳工艺参数为:Fe3Al含量(质量分数)为15%,成形压力为2488MPa,烧结温度为1380℃.此条件下制备的复合材料的各项力学性能较好:相对密度为93%,维氏硬度为9.3GPa,断裂韧度为7.51MPa·m1/2.烧结温度对提高复合材料力学性能的影响较大.     

机械合金化制备(Al_2O_3+Gr)/Cu复合材料的性能

采用机械合金化制备Al2O3、Gr(石墨)双相强化Cu基复合材料((Al2O3+Gr)/Cu),研究球磨时间对复合材料组织与性能的影响。结果表明:球磨时间为9 h时,细长条状的Gr和纳米Al2O3颗粒弥散分布在Cu基体中,(Al2O3+Gr)/Cu复合材料具有最佳的综合性能,相对密度、硬度、导电率、摩擦系数和体积磨损率分别为95.3%、142 HV、39.8%IACS、0.15和1.4×10-3mm3/m;球磨时间对(Al2O3+Gr)/Cu复合材料的摩擦系数影响较小,体积磨损率则随着球磨时间的延长先增大后减小,与Al2O3/Cu复合材料相比,(Al2O3+Gr)/Cu复合材料具有优良的减磨耐磨性能。     

烧结工艺对Ti/Al2O3复合材料性能的影响

本文利用放电等离子烧结技术探讨了烧结温度和保温时间对40%Ti(体积分数)/Al2O3(体积分数)复合材料性能的影响.实验结果表明复合材料的性能受烧结温度的影响最为显著,过度的延长保温时间会使晶粒发生异常长大,使得复合材料性能降低.烧结温度1 300℃,保温8 min,制备的复合材料力学性能最佳,其弯曲强度、断裂韧性、显微硬度和相对密度分别为1002.22 MPa、19.73 MPa*m1/2、18.14 GPa和99.74%.     

Al2O3粉末对MA-SPS制备Fe3Al材料显微组织的影响

采用机械活化-放电等离子烧结(MA-SPS)方法制备了Fe3Al材料,使用X射线衍射仪和电子显微镜对球磨粉体和烧结块体进行了研究。球磨之前加入纳米Al2O3粉末可以有效地细化烧结材料的显微组织,提高其力学性能。加入2%～5%(质量分数,以下同)Al2O3时,对显微组织的细化作用明显,材料的显微硬度提高,超过5%时,孔隙度上升,显微硬度下降。     

球磨工艺对Al2O3/Mo复合材料组织的影响

针对原位自生Al2O3增强钼基复合材料晶粒较大的问题,采用溶胶-凝胶与高能球磨相结合的方法细化复合材料晶粒,并利用SEM、XRD对不同球磨工艺所制备Al2O3/Mo复合粉末及复合材料的组织进行了观察和分析。结果表明:随着球磨时间的延长,Al2O3/Mo复合粉末颗粒由球状变为层片状再成为细小的球状,颗粒大小由约1.5μm细化为约500nm,其中的钼晶粒不断细化;高球料比所得粉末的分散性和破碎细化程度较好;转速提高使得粉末颗粒的尺寸均匀程度降低,且伴有结块现象,不利于粉末的细化。在球料比5∶1、转速300r/min、球磨时间60h条件下获得的复合粉末,经压坯烧结可制备出Al2O3颗粒为纳米级的钼基复合材料。     

电场活化烧结制备Cu-10Cr-0.5Al_2O_3复合材料

对Cu-10Cr-0.5Al2O3(质量分数,%)混合粉末及球磨复合粉末,采用电场活化烧结技术制备高强高导电铜基块体材料,并研究脉冲峰值电流和通电烧结时间对烧结材料组织和性能的影响。结果表明,随着脉冲峰值电流增大,烧结材料的相对密度和导电率均提高,相对密度最高可达99%,硬度和抗弯强度则先上升后下降。当脉冲电流峰值为2.94 kA时,烧结材料具有较好的综合性能,相对密度、硬度、抗弯强度和电导率分别为97.5%、285HV、911MPa和50IACS%;随着通电烧结时间延长,烧结材料的密度、硬度、抗弯强度和导电率均逐渐上升,但烧结时间过长会引起硬度轻微下降;对Cu-10Cr-0.5Al2O3混合粉末进行球磨虽导致烧结材料的电导率下降,但可显著提高材料的硬度和抗弯强度。     

原位反应合成致密Al2O3p-TiCp/Al复合材料

本文采用高能球磨、原位反应合成及热压技术制备了致密的Al2O3p-TiCp/Al复合材料,并用XRD、SEM以及EDAX等手段分析了复合材料的相组成、显微组织.结果表明:Al-TiO2-C三元体系在热压反应烧结后,可制得致密度较高的Al2O3p-TiCp/Al原位复合材料,其显微组织中Al2O3和TiC颗粒尺寸为1μm左右,分布均匀.高能球磨有利于增强颗粒细化弥散分布和反应进行完全.     

球磨时间对放电等离子烧结合成Ti_3SiC_2纯度的影响

本文采用原料配比为3Ti/Si/2C/0.2Al(摩尔比)的单质混合粉体为原料,进行机械合金化(MA)和随后的放电等离子烧结(SPS),以制备高纯Ti3SiC2陶瓷,研究了球磨时间对放电等离子烧结制备Ti3SiC2的影响。结果表明,机械合金化混合粉体后,粉体颗粒明显细化。球磨10h,单质混合粉体会发生化学反应,生成TiC,Ti3SiC2混合粉体。继续球磨至20h,生成物混合粉体会显著细化。球磨时间对SPS烧结合成Ti3SiC2有显著的影响。球磨10h,即反应刚刚完毕,最有利于SPS合成致密高纯的Ti3SiC2,球磨时间较短(5h),对Ti3SiC2陶瓷的烧结促进作用不显著,而反应后继续延长球磨时间至20h,会降低烧结体中Ti3SiC2的纯度。采用球磨10h的粉体为原料,经850℃放电等离子烧结可获得纯度高达96%(质量分数,下同)的Ti3SiC2疏松块体,烧结温度提高到1100℃,可获得纯度为99.3%、相对密度高达98.9%的TiSiC致密块体。     

W-10%TiC复合材料的制备与力学性能研究

采用高能球磨手段制备了W-10%TiC(质量分数, 下同)纳米复合粉体, 并采用热压方法烧结成致密块体, 研究了高能球磨、烧结温度、烧结时间及烧结压力对复合材料致密度和力学性能的影响. 结果表明: 高能球磨后, 复合粉体的颗粒形状近似球形, 粒径均匀, 平均粒径为100 nm, 并且纳米复合粉体的烧结温度大大降低, 其原因是粉体的颗粒细小、扩散系数高、表面能高等性质及球磨过程中少量Fe, Ni杂质的引入. 对所制备纳米粉体而言, 较合适的烧结工艺为: 1700 ℃, 30 Mpa压力下烧结60 min, 在此工艺条件下制备的复合材料的致密度达到98.4%, 抗弯强度和断裂韧性分别达到: 681 Mpa, 6.24 Mpa·m1/2.     

China's Major Non-ferrous Metals Imports & Exports

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Zinc Production by Province in 2014

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80% of Chinese Firms Purchasing Overseas Mines Ended up in the Red

<正>Minmetals Resources acquired the world’s largest copper mine under construction for USD5.85 billion.One after another,listed companies Jien Nickle,China Molybdenum and Chihong Zinc and Germanium raised money to get involved in overseas mining projects…SOEs and private enterprises are engaged in a frenzy of overseas mine purchasing.A reporter with Economic     

Copper Processing Profit Dropped Sharply,Copper Consumption Will Face Impact in the Second Half of the Year

正Judging from China’s copper consumption field,the biggest consumption unit is electric power,which accounts for 47%of total consumption;it is followed by light industry sector,including household electrical appliance,machinery,durable goods and hardware etc,which accounts for 22%of total consumption;followed by transportation field,     

Central Geological Prospecting Fund Newly Added 16.47 Million Tonnes of Bauxite in 2013

正In 2013,the Central Geological Prospecting Fund(CGPF)Project newly discovered 15 ore fields,including 3 large above ore fields,and 5medium sized ore fields.The reporter learned from the recently published"Annual Report of Central Geological Prospecting Fund Project(2013)"that,from 2006 to 2013 the CGPF     

Manufacturers of Copper Tube for Central Air Conditioner Use Face Mounting Pressure in the Final Quarter of the Year

正This year,the investment growth rate of real estate industry continued to slow down,sold area of commercial housing also dropped significantly,which brought huge pressure to the domestic air conditioning manufactures.In the first half of the year,by relying on high growth in national financial expenditure,along with investment in public infrastructure     

Xinjiang Ranks No.1 in Production of Primary Aluminum in China

正Kang Yi,Honorary Chairman of China Nonferrous Metals Industry Association,said recently at the Forum on Development of the Non-ferrous Metals Industry in Central and Western China held in Zhengzhou that,as more and more electrolytic aluminum factories in Xinjiang came into operation,the electrolytic aluminum output of Xinjiang had reached2,275,000 tons in the first 7 months this year,     

Shenhuo Coal Industry and Electricity Power Completed800,000 t/a Aluminum Project in Xinjiang

正"Xinjiang project has been completed according to schedule,but total completion and total start of production are two different concepts,after completion it still needs a gradual process of reaching production target."On the morning of November 3,Shenhuo Coal Industry and Electricity Power told investors the above statement on the investor interaction platform.     

Guangdong Metal Transaction Center has Become the Second Largest Precious Metal Transaction Platform Nationwide

正The reporter learned from Guangdong Province Precious Metal Transaction Center that in 2013the Center maintained healthy development momentum,and had become the second largest precious metal transaction platform in China in terms of market size;currently Guangdong is quickening steps of financial innovation for the Center,aiming to build a transaction center with international core competitiveness.     

Seven Rare Earth Projects Involving Close to 3 Billion Yuan Investment Landed In the HighTech Zone

正On May 22,Baotou Rare Earth Industry Cooperation Consultation MeetingProject Agreement-signing Ceremony was held in Ningbo,nearly 40 enterprises from Ningbo,Guangdong,Hunan,and Shanxi participated in project consultation.After multi-lateral communication,agreements were signed for a total of 7 rare earth projects successfully.