活性填料对聚碳硅烷基悬浮液直写成形3D碳化硅的影响

分别采用纳米钛粉(Ti)和氧化亚镍粉(NiO)为活性填料,聚碳硅烷(polycarbosilane,PCS)为碳化硅(SiC)陶瓷先驱体,以正己烷作为溶剂制备浆料,然后通过3D直写成形和高温裂解制备SiC陶瓷基复合材料,对浆料的流变性能以及SiC陶瓷基复合材料的物相和微观形貌进行表征,研究活性填料纳米Ti粉和纳米NiO粉对3D-SiC陶瓷基复合材料的物相与微观形貌的影响。结果表明,浆料的黏度与PCS的质量分数成正比,具有剪切变稀现象,w(PCS)为75%的浆料具有稳定的打印性能。纳米Ti粉可有效降低成形坯体热处理过程中的质量损失率和线收缩率。随m(Ti)/m(PCS)的值从0增加到1.0,1 450℃高温裂解后陶瓷的质量损失率和线收缩率分别由18.29%和24.38%降低至14.05%和12.13%,所得陶瓷包含Ti C和SiC两相,相比于Ti粉,NiO可作为SiC的表面修饰催化剂,并通过气-液-固(V-L-S)生长机制使SiC陶瓷表面原位生长SiC晶须团簇。     

反应烧结碳化硼低压注射成型用浆料粘度的研究

针对反应烧结B_4C陶瓷材料低压注射成型用浆料的制备问题,研究了颗粒级配、分散剂含量(质量分数)和B_4C固含量对浆料粘度的影响.研究结果表明:当B_4C粉体颗粒级质量比为m_((F320))∶m_((F800))=6∶4,分散剂质量分数为1%,B_4C固含量(质量分数)为80%时,浆料的粘度适合于低压注射成型,低压注射成型坯体中B_4C颗粒分散均匀,坯体的体积密度为1.79 g/cm~3,气孔率为2.07%,脱蜡坯体显微结构较为均匀.脱蜡坯体经过1550℃渗Si烧结后,材料的抗弯强度、断裂韧性、维氏硬度分别可达322.7 MPa、3.33 MPa·m~(1/2)、25.7 GPa.本实验通过控制颗粒级配,分散剂含量及B_4C固含量实现了低粘度、高固含量B_4C(w(B_4C)=80%)浆料的制备,并有效地提高了脱蜡坯体和反应烧结B_4C复合材料的性能.     

助剂用量对反应烧结碳化硅结构及力学性能的影响

以碳化硅、碳黑和石墨为原料, 聚乙烯吡咯烷酮K90、K30为分散剂, 聚甲基丙烯酸铵CE-64为减水剂, 采用注浆成型工艺制备碳化硅素坯, 并在1700℃下对素坯进行反应烧结制备碳化硅成品, 研究了分散剂、减水剂用量对浆料黏度、素坯密度、素坯孔隙率和成品微观组织及力学性能的影响。结果表明: 随着助剂用量的增加, 浆料黏度总体上呈现下降趋势, 素坯密度呈先降后升趋势, 素坯孔隙率呈先升后降趋势。当K90、K30、CE-64的质量分数分别为3.8%、2.0‰、4.3‰时, 所得素坯的孔隙分布均匀, 素坯中碳化硅分布较为疏松, 渗硅通道较多, 有利于碳和硅粉的充分反应, 获得的烧结制品性能优良。     

原位凝固制备铁-莫来石复合材料坯体

介绍了用原位凝固注模成形法制备铁-莫来石复合材料坯体的基本工艺过程,研究了复合材料浆料的固相含量、原位凝固剂等对坯体性能的影响。结果表明,原位凝固剂可使浆料原位凝固,通过调节固相含量、凝固剂、缓冲剂可以控制凝固时间和坯体的强度,坯体具有密度较高且均匀,足够的脱模强度,尺寸变化率小等特点。     

浆料注射法制备Cf/SiC-ZrC复合材料的力学和抗氧化性能

以 SiC 粉和 ZrC 粉为原料,配制固含量体积分数为 30%的水基陶瓷浆料,分别采用浆料注射法和真空浸渍法将浆料引入到密度为 0.2 g/cm³的碳纤维预制体中,结合化学气相渗透和反应熔渗工艺制备 C_f/SiC-ZrC 复合材料。观察分析素坯和 C_f/SiC-ZrC 复合材料的形貌与组织结构,测定复合材料的密度、开孔率、抗弯强度和抗氧化性能等。结果表明,相比真空浸渍法,浆料注射法能一次将 SiC 粉和 ZrC 粉均匀引入碳纤维预制体中,坯体体积一次填充率为 37.3%。注射法制备的复合材料平均密度为 2.91 g/cm³,中心和外层的抗弯强度相差较小,分别为41.12 MPa 和 43.90 MPa,材料的断裂方式均表现为假塑性断裂。样品在空气中氧化 120 min 后,表面形成较连续致密的氧化层,氧化趋于平衡稳定,表现出较好的抗氧化性能。     

凝胶注模法制备复杂形状钨铜复合材料

利用非水基体系凝胶注模法制备了复杂形状钨铜复合材料坯体。研究了分散剂含量以及固相含量对钨铜浆料黏度的影响,绘制了坯体的室温干燥曲线并制订了干燥制度,同时对坯体微观形貌、抗弯强度等进行了表征和测试。结果表明:分散剂添加量为0.15%(质量分数,基于金属粉末质量)时浆料黏度达到最低,在此基础上浆料的固相含量可达到45%(体积分数),满足凝胶注模的要求;坯体先在室温下干燥10h后放入100℃的恒温干燥箱中干燥8h,可得到表面无变形、无开裂的钨铜坯体;随着固相含量的增大,坯体致密性和均匀性均随之提高;坯体表面质量较好,抗弯强度可达到26.9 MPa。     

凝胶离心成形制备YG10硬质合金管

将凝胶离心成形工艺应用于YG10复合粉末的坯体成形,研究了固含量对YG10复合粉末浆料的流变性的影响,分析了凝胶离心成形过程中引发剂量和压力对聚合速率的影响,并研究了离心转速对坯体和烧结体性能的影响。结果表明:以油酸作分散剂,制备稳定且流动性好的浆料最佳固含量为50%(体积分数),引发剂的加入量为5mmol/L(相对于预混液的体积),凝胶离心成形过程中压力能够加速浆料的固化,采用自行设计的离心成型机,选择最佳转速4 000r/min,制备出的坯体密度高、无残留气孔,相对密度57%,强度28.3MPa。坯体经真空脱胶烧结1 420℃保温1h制备出YG10硬质合金管,烧结体收缩均匀无变形,组织结构完整无偏析。     

TiB2/SiC陶瓷复合材料制备工艺的研究

以TiO2、B4C和C为原料,基于原位合成法在SiC基体中生成TiB2颗粒,并采用无压烧结法制备出TiB2/SiC复合陶瓷.通过对复合材料制备工艺的研究,发现:高于1 300℃的预烧结能形成TiB2/SiC复合陶瓷坯体.C含量、烧结温度和保温时间对复合材料的相对密度均有影响.当C含量(质量分数)为4%时、在1 400℃...     

SiC粒度及粉末装载量对SiCp/Al复合材料热循环行为及力学性能的影响

选用4种不同粒度的SiC分别与平均粒度为14 μm的SiC粉末混合,混炼后得到4种不同粉末装载量(体积分数)的喂料,采用粉末注射成形方法制备成SiC坯体,再无压熔渗Al～12%Si～8%Mg合金,获得高体积分数SiCp/Al复合材料,研究SiC粉末粒度及SiCp/Al复合材料中SiC的体积分数(即注射成形喂料中SiC粉...     

凝胶离心成形制备TiC-FeCrMo硬质合金

将凝胶离心成形工艺应用于TiC-FeCrMo硬质合金的坯体成形,研究了固含量对TiC-FeCrMo复合粉末浆料的流变性的影响,分析了凝胶离心成形过程中压力和聚合速率的关系,并研究了离心转速对坯体和烧结体性能的影响。结果证明:HEMA凝胶体系对TiCFeCrMo复合粉末具有很好的分散性,以油酸作分散剂,制备稳定且流动性好的浆料的最佳固含量为55%(体积分数),凝胶离心成形过程中压力能够加速浆料的固化,采用自行设计的离心成形机,选择最佳转速2 000r/min,制备出大尺寸棒状钢结合金坯体,坯体密度高、无残留气孔,强度高达30MPa,密度为4.07g/cm3,坯体经过真空脱胶烧结一体化烧结,1 420℃保温1h制备出钢结硬质合金烧结体,其密度为6.52g/cm3,抗弯强度1 580MPa。     

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.