VC抑制剂对激光熔覆原位生成WC增强Ni基涂层的影响

在H13钢表面通过激光熔覆原位生成不同VC含量的WC增强Ni基涂层,研究VC抑制剂对WC晶粒的细化作用及其对涂层硬度和耐磨性的影响。分别采用XRD、SEM、EDS分析涂层物相、形貌及成分分布。采用显微硬度计测定涂层硬度,摩擦磨损实验机测试涂层耐磨性。结果表明,VC具有明显的抑制WC晶粒长大的作用,且当VC含量为10%时,抑制效果最佳;不同VC含量的涂层硬度均高于无VC的涂层,当VC含量为15%时涂层具有最高的硬度;10%VC+(W+C)+Ni60涂层、(W+C)+Ni60涂层和Ni60涂层的耐磨性依次下降。VC能够使原位生成WC晶粒的析出机制受到阻碍,导致晶粒细化;加入的VC也可能沉积在WC晶粒上,阻止其进一步长大。适量的VC可对WC增强相的长大起到明显的抑制效果,并改善涂层的硬度和耐磨性。     

SHS-离心法制备W-C-Fe金属陶瓷内衬复合钢管

以Fe₂O₃、WO₃、Al和C为反应原料,采用SHS-离心法制备W-C-Fe内衬复合钢管.利用X射线衍射分析内衬层的相组成,扫描电镜观察金属陶瓷涂层的组织,利用能谱仪分析涂层与基体结合处的元素分布,显微硬度仪测量内衬层硬度.结果表明:涂层与基体之间形成良好的冶金结合,涂层主要由Fe₃W₃C组成,还有少量的WC、W₂C、Fe₃C和Fe;涂层组织呈梯度分布,靠近基体处晶粒细小,远离基体处晶粒呈粗大树枝状;涂层显微硬度为13.5±1.6GPa,是基体的7~8倍.     

42CrMo钢表面高频感应熔覆WC增强镍基复合涂层的研究

通过高频感应加热在42CrMo钢表面熔覆制备0.5 mm厚的WC增强Ni60复合涂层。通过电子显微镜、显微硬度计、能谱仪、X射线衍射仪以及万能摩擦磨损实验机研究分析了图层的组织形貌、相结构、硬度和耐磨性。结果表明:熔覆层组织均匀,主要由WC、W_2C、Cr_(23)C_6、Cr_7C_3、FeNi、Ni_3Fe等相组成,与基体呈冶金结合并伴随有大量合金元素的扩散,结合界面较致密,无明显夹杂等缺陷,结合强度高;熔覆层组织致密,硬度分布较为均匀,WC增强Ni60复合熔覆层耐磨性相比淬火态42CrMo有较大提高。     

高功率半导体激光宽带熔覆WC-NiSiB耐磨涂层的组织结构与性能

采用3kW高功率半导体激光器,在45钢基体上制备不同WC含量(质量分数20%~80%)的WC-NiSiB复合涂层,用扫描电镜(SEM)、能谱仪(EDS)及X射线衍射(XRD)对熔覆层的微观组织、成分分布及物相进行表征,并测试涂层试样的硬度与耐磨性能。结果表明,激光熔覆WC-NiSiB复合涂层组织主要由γ-Ni、WC、W2C、WB、W2B、Ni4B3及Ni4W等物相组成,熔覆层与基体形成冶金结合。涂层与基体的结合区,从熔合线开始逐渐向上的组织依次为垂直于界面的胞状晶、柱状晶和枝状晶,熔覆层中部为沿一定方向生长的树枝晶,表层为异向生长的细小树枝晶。随WC颗粒含量增加,涂层中WC颗粒分布更加密集。WC含量为60%时,WC颗粒分布均匀致密,熔覆层无裂纹,熔覆层的硬度最高达到1291HV,为NiSiB合金层硬度的2.7倍,耐磨性是NiSiB合金层的6.8倍。     

铁基合金粉末中碳化硼添加量对喷焊层性能的影响

为了提高铁基合金喷焊层的硬度与耐磨性,在铁基合金粉末中加入不同含量的碳化硼,采取火焰喷焊技术在42CrMo合金钢表面制备四种复合粉末喷焊层,然后用光学显微镜对喷焊层的显微组织进行分析,利用自动转塔显微硬度计、磨粒磨损试验机测定了喷焊层的显微硬度和耐磨性。实验结果表明:铁基喷焊层与基体形成了良好的冶金结合,涂层主要由细小的树枝晶及鱼骨状共晶组织组成;B4C的加入可显著提高喷焊层的硬度和耐磨性,细化组织,随着B4C含量的增加,喷焊层的硬度和耐磨性呈现先增加,后降低的趋势,当B4C含量为2%时,喷焊层的硬度和耐磨性最好。     

超高速激光熔覆316L涂层的组织与性能

采用超高速激光熔覆技术,在45钢轴上制备了316L涂层;利用扫描电镜(SEM)观察了涂层的显微组织,用能谱仪(EDS)和X-射线衍射(XRD)进行元素及物相分析,并测试了涂层的显微硬度和耐磨性。结果表明,超高速激光熔覆技术的光斑直径小、搭接率高,故涂层的平整度高;能量密度高(约9×10⁴W/cm²),粉末完全熔化,故涂层的致密度高;熔体的体量小,冷热转换速度快,过冷度△T大,晶粒细化明显;涂层中下部由快速凝固产生的细小枝晶以及枝晶间共晶相组成,中上部的晶粒逐渐向等轴晶粒转变;搭接分界处和熔覆层/基材界面处,两边的晶粒尺寸差异较大;激光对基材有一定的稀释作用;涂层厚度不均匀,与基材结合良好,为冶金结合;316L涂层物相由γ-Fe、Cr_0.19Fe_0.7Ni_0.11、Fe₆₃Mo₃₇组成;由于细晶强化和第二相强化机制,316L涂层的平均硬度(634.12HV_0.5)是45钢基体的3.07倍;耐磨性提高了31.8%,其...     

现场激光增材修复风机转子轴实验及组织性能研究

大型风机是煤矿井下安全生产的重要设备, 由于高速旋转, 转子轴经常出现损伤问题, 对其修复具有重 要经济价值。 本文利用 4kW 高功率半导体激光器, 在 45 钢基体上进行修复工艺试验, 分别用扫描电镜 (SEM)、 能谱仪 (EDS)、 X 射线衍射 (XRD) 及硬度计对修复层的微观组织、 成分分布、 物相及硬度进行表征, 确定最佳工 艺参数并进行激光现场修复。 结果表明, 涂层厚度约为 1.45μm, 涂层与基体呈冶金结合; 涂层底部晶粒以近似 垂直于基体界面的胞状晶形态生长, 中部以具有一定生长方向的柱状晶过渡到枝晶, 上部是各向异性生长的树枝 晶; 涂层物相主要由 γ -Ni 固溶体、 Fe3Ni2 金属间化合物及 Cr-Ni-Fe-C 等组成; 扫描速度为 8mm/s 时, 涂层组织 均匀致密、 晶粒细小, 显微硬度为 200 HV0.5, 较为稳定; 风机转子轴修复质量较好, 能够满足使用要求。     

喷雾转换法制备超细晶WC-12Co复合粉末HVOF涂层性能研究

采用超音速火焰喷涂(HVOF)技术,以喷雾转换法制备的超细晶WC-12Co复合粉末为热喷涂粉末原料,在45#钢基体上制备WC-12Co涂层,并测试涂层的显微硬度、开裂韧性及抗磨粒磨损性能,利用XRD对复合粉末及涂层进行相结构分析,用SEM对复合粉末及涂层截面进行显微观察。结果表明,在喷涂过程中,多孔空壳球形复合粉末中WC颗粒有明显的脱碳分解发生,涂层中含有W2C、Co2W4C、W和非晶相;涂层组织呈典型的层状结构,WC晶粒有圆润化和长大现象;涂层显微硬度HV0.3/10平均值为1 084、开裂韧性平均值为5.24 MPa·m1/2,涂层表面抗磨损性能随粗糙度降低和硬度增加而提高,平均磨损质量损失为0.783mg/min。     

超音速火焰喷涂涂层及耐磨性能研究

采用超音速火焰喷涂方法在45号钢基体上制备了NiCr、316L、10Co4Cr/WC、12Co/WC等4种涂层,对涂层组织进行了金相观察,测试了涂层的硬度及耐磨性。结果表明,上述涂层与45号钢基体界面结合良好,孔隙率为0.50%~2%,平均厚度20μm左右,不同涂层硬度及耐磨性顺序为:10Co4Cr/WC>12Co/WC>(45号钢基体)>316L>NiCr20。     

CeO2添加量对45钢表面激光熔覆Ni-WC涂层的组织和性能影响

利用二氧化碳激光器在45钢基体表面上熔覆Ni-WC-CeO₂的复合涂层,使用扫描电镜、EDS、显微硬度计、洛氏硬度计,研究CeO₂添加量对Ni-WC-CeO₂复合涂层宏观形貌、显微组织、元素分布、表面硬度及纵截面显微硬度的影响,以找到最佳的CeO₂添加量。CeO₂的添加有助于改善涂层宏观形貌、基体和涂层的扩散及浸润性,细化微观组织及WC形貌,提高涂层表面硬度和纵截面显微硬度。CeO₂添加量存在一个最佳值：当CeO₂添加量为0.3%时,Ni-WC-CeO₂复合涂层表面无渣、无裂纹、较小润湿角,宏观形貌最好,从表面到与基体结合处涂层显微组织无枝晶,组织明显细化,Ni-Cr合金与WC间、涂层与基体间的元素发生明显互扩散,碳化钨形貌细化且分布较为均匀,涂层表面硬度最高,所有涂层纵截面显微硬度均呈现中间高两端低的“山形”分布;当CeO₂添加量为0.25%时,每组纵截面显微硬度几乎都高于其他CeO     

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.