超音速火焰喷涂WC-10Co4Cr 涂层组织及耐磨耐蚀性研究

采用超音速火焰喷涂工艺在不同喷涂距离下制备了WC-10Co4Cr涂层,并对其组织结构及耐磨耐腐蚀性能进行了研究。利用金相显微镜、扫描电子显微镜、X射线衍射仪分析了涂层的组织结构和相组成,并测试了涂层显微硬度、孔隙率;对涂层磨损表面进行了观察分析,探讨了涂层的失效形式。结果表明,喷涂距离对涂层的组织结构及耐磨性具有一定影响。适当增加喷涂距离,粒子由于在焰流中停留时间增加而使熔化程度加大,撞击基体后扁平化现象明显。因此,涂层的致密度、耐磨性、耐腐蚀性都有所提高。当喷涂距离为380mm 时,涂层呈现出较好的耐磨性及耐腐蚀性。     

超音速火焰喷涂两种WC-17%Co涂层的组织和性能研究

采用超音速火焰喷涂法制备纳米和普通WC-17%Co涂层,借助于SN-3400型扫描电镜(SEM)、D8型X射线衍射仪(XRD)、HXD-1000TM型显微硬度计、SHT4605型拉伸试验机和TRB型球盘磨损试验机对涂层组织结构、相组成、显微硬度、结合强度及耐磨性能进行了分析.结果表明,两种WC-17%Co涂层形成过程中WC发生了分解,并形成了W2C、W和CoxWyCz(Co3W3C、Co3W9C4)等一些新相,纳米涂层的组织形态明显好于普通涂层,组织晶粒细小,WC晶粒保持在120~150 nm的纳米尺度范围;纳米涂层的显微硬度、结合强度和耐磨性都高于普通涂层,相比之下,纳米涂层的显微硬度、结合强度比普通涂层高出近30%,在相同的试验条件下普通涂层的磨损体积是纳米涂层的2倍.     

碳钢WC—10Co-4Cr复合涂层的组织及性能研究

采用AC—HVAF热喷涂设备，在碳钢表面喷涂WC-10Co-4Cr复合涂层。用电子显微镜、X射线能谱分析仪、金相显微镜和磨损实验研究了涂层的均匀性、硬度、显微组织、化学成分、结合区形貌和相对耐磨性。结果表明：涂层厚度均匀、组织致密、硬度可达1200HV200；涂层与碳钢结合良好，没有孔洞，界面相容性良好；涂层试样的耐磨性比45钢的耐磨性优良。     

枪速对热障涂层组织性能及残余应力的影响

为了研究等离子喷涂制备热障涂层(TBCs)时不同枪速对陶瓷面层组织性能和残余应力的影响,在GH4169高温合金基体上采用超音速火焰喷涂(HVOF)Ni Co Cr Al Y粘结层(BC层)和大气等离子喷涂(APS)8YSZ陶瓷层(TC层).通过对比不同参数样品的微观组织以及显微硬度、残余应力和热震性能差异,研究了枪速对热障涂层的影响.结果表明:枪速过低或过高时,涂层表面残余应力较大,热震性能较低;随着枪速的增大,涂层表面粗糙度逐渐增大,而孔隙率和显微硬度逐渐减小;枪速过低时,涂层出现纵向裂纹,热震失效方式为整体剥落;而枪速较大时,涂层从边缘向中心不断剥落,涂层表面出现白点.     

纳米WC/12Co涂层在轴流式引风机叶片防磨上的研究

采用超音速火焰喷涂工艺分别制备了纳米结构和微米结构的WC/12Co涂层.通过和传统轴流式引风机叶片抗冲蚀涂层的比较,研究分析了两种涂层的显微硬度、金相结构、结合强度和抗冲蚀磨损性能.结果表明:超音速火焰喷涂WC/12Co涂层性能优于传统抗冲蚀涂层,其中纳米结构涂层性能更加优越.     

TC4基体等离子喷涂WC-Co涂层的工艺研究

采用不同的工艺参数对TC4合金试样进行等离子喷涂WC．Co涂层,对所喷涂的试样进行金相分析和孔隙率测定试验,根据涂层金相照片的氧化物、致密均匀程度以及涂层的孔隙率数值等确定合适的工艺参数．在对此参数下所喷涂的涂层进行结合强度、硬度等性能检验,测得结合强度最低值为38．45MPa,硬度最小值为83,均超过实际要求值．对涂层进行耐磨损比较实验,实验结果表明,此参数下所喷涂的涂层能够很好的满足实际需要．     

HVOF燃料混合比对粒子飞行特性及涂层性能的影响

目的 研究在HVOF热喷涂中不同的氧气(O)与燃料(F)的体积混合比对WC-Co合金粉末颗粒飞行速度和温度及涂层表面性能的影响.用实验和理论分析方法确定合理的氧气与煤油的体积混合比例,取得最佳涂层质量.方法 采用Spray Watch系统对HVOF喷涂过程中WC-Co合金粉末颗粒飞行速度和温度进行测量,建立在不同氧气与煤油的体积混合比条件下颗粒飞行速度和温度与喷嘴距离关系,同时采用实验分析方法对涂层的硬度、摩擦系数和表面粗糙度进行了测量和分析.结果 粒子的飞行速度和温度受到HVOF热喷涂中氧气与煤油的体积混合比的影响,当O/F为0.9时,粒子的速度和温度相对于O/F比值为1和1.1的要大.结论 WC-Co合金粉末在喷涂过程中为液固两相流,粒子距喷嘴100～250mm范围内温度和速度都达到最大值.O/F比值对表面硬度和粗糙度影响较大.     

大气压下等离子体喷涂制备Cu/W涂层性能研究(英文)

采用大气压等离子体喷涂和高速大气压等离子体喷涂技术制备Cu/W涂层,分别对该涂层断面的表面形貌、孔隙率、氧含量和结合强度进行测试分析.结果表明,高速大气压等离子体喷涂技术制备的Cu/W涂层在孔隙率和氧含量方面突显优势.采用高速大气压等离子体喷涂技术制备的Cu/W涂层孔隙率低于3%,且大部分孔径均小于1μm,利用EDS测得的W涂层氧含量为w(O)=0.41%,该值与真空等离子体喷涂制备的W涂层含氧量接近.与真空等离子体喷涂技术相比,高速大气压等离子体喷涂制备W涂层技术的复杂性和制作成本显著降低,在工程应用中实用可行.     

等离子喷涂Ni_5Al-Al_2O_3复合涂层的耐磨损及耐腐蚀性研究

用大气等离子喷涂(APS)技术在3种不同工艺参数条件下制得Ni_5Al-Al_2O_3复合涂层。采用扫描电镜(SEM)对涂层的组织结构进行了表征,分别用FM-700型显微硬度分析仪和M-200型磨损试验机测定了涂层的显微硬度和耐磨性能,用Lviumastat电化学分析系统测试了涂层的耐腐蚀性能。结果表明:采用50V-550A/600A/650A电流参数所制备的涂层均呈层片状结构,随着喷涂电流的增加,涂层的显微硬度逐渐增大、孔隙率逐渐降低,涂层的耐磨损性能提高。涂层的耐电化学腐蚀性能与涂层的孔隙率有关。     

高速火焰喷涂多功能梯度玻璃涂层的工艺研究

针对船舶部分管件的耐海洋腐蚀,又减少小剂量的^y射线与中子照射的要求,研究了高速火焰喷涂一种新型多功能梯度玻璃涂层,其组成依次为WC—Co—Ni／B—cr—Fe／B—cr—Ni／WC—Ni—B—Cr!玻璃．通过对工艺参数的分析研究,即可以保证此玻璃涂层的制备,又保障涂层与基材、涂层之间的结合性能,具有广阔的应用前景．     

Research on Ultrafine WC-lOCo Cemented Carbide with High Properties

WC- 10Co nanocomposite powder produced by spray pyrolysis-continuoas reduction and carbonization technology was used, and the vacuum sinteriag plus sinterhip process was cdopted to prepare ultrafine WCCo cemented carbide. The microstructure, grain size, porosity, density, Rockwell A hardness （ HRA ）, transverse rupture strength （ TRS ） , saturated magnetization and coercivity force were studied. The experimental results show that average grain size of the sample prepared by vacuum sintering plas sinterhip technology was about 420 nm, transverse rupture strength was more than 3460 MPa, and Rockwell A hardness of sintered specimen was more than 92.5. Ultrafine WC- 10Co cemented carbide with high strength and high hardness is obtained.     

Influences of Carbon Content on the Properties and Microstructure of Ultrafine WC-10Co Cemented Carbide

WC-10Co nanocrystalline composite powders prepared by spray pyrogenation-continuous reduction and carburization technology were consolidated by vacuum sintering plus hot isostatic pressing (HIP). Influences of carbon content on properties and microstructure of ultrafine WC-10Co cemented carbide were investigated. The results show that the relative density of the ultrafine WC-10Co cemented carbides can reach 99.72%, and the transverse rupture strength (TRS) was higher than 3 890 MPa, Rockwell A hardness (HRA) was higher than 92.5, the average grain size was less than 460 nm, when carbon content in nanocrystalline composite powder was 5.54wt% and the ball-milled time was 48 hours, ultrafine WC-10Co cemented carbide with excellent properties and homogeneous microstructure was obtained. Funded by the National Natural Science Foundation of China (No.50502026), the Youth Science Plan for Light of the Morning Sun of Wuhan City(No.200750731270), and Key Project for the Science & Technology Research Department, Chinese Ministry of Education (No.105123)     

Influences of Carbon Content on the Properties and Mierostrueture of Ultrafine WC-10Co Cemented Carbide

WC-10Co nanocrystalline composite powders prepared by spray pyrogenation-continuous reduction and carburization technology were consolidated by vacuum sintering plus hot isostatic pressing （HIP）. Influences of carbon content on properties and microstructure of ultrafine WC-10Co cemented carbide were investigated. The results show that the relative density of the ultrafine WC-10Co cemented carbides can reach 99.72%, and the transverse rupture strength （TRS） was higher than 3 890 MPa, Rockwell A hardness （HRA） was higher than 92.5, the average grain size was less than 460 nm, when carbon content in nanocrystalline composite powder was 5.54wt% and the ball-milled time was 48 hours, ultrafine WC-10Co cemented carbide with excellent properties and homogeneous microstructure was obtained.     

预烧结对低压烧结WC-Co硬质合金组织和性能的影响

采用原位还原碳化反应制备超细WC-10%Co,在1250、1300、1350、1380℃进行预烧结处理,得到的预烧结块体在1450℃、5 MPa氩气条件下进行低压二次烧结;分析对比了预烧结块体和二次烧结块体的显微组织,并对二次烧结合金进行了性能测试.结果表明:不同温度预烧结块体经低压二次烧结后,可有效抑制晶粒异常长大现象,二次烧结后合金具有高的断裂韧性,最高值达16.1MPa·m-1/2.在1 350、1 380℃下预烧结块体经低压二次烧结后均具有均匀的合金组织,其中经过1380℃预烧结块体横向断裂强度为3260 MPa.     

Atomic force microscope study of WC-10Co cemented carbide sintered from nanocrystalline composite powders

In order to compare the spark plasma sintedng （SPS） process plus hot isostatic press （HIP） with vacuum sintedng plus HIP, an investigation was carried out on the topography, microstructure and gain size distribution of nanocrystalline WC-10Co composite powder and the sintered specimens prepared by SPS plus HIP and by vacuum sintering plus HIP by means of atomic force microscopy （AFM）. The mechanical properties of the sintered specimens were also investigated. It is very easy to find cobalt lakes in the specimen prepared by vacuum sintering plus HIP process. But the microstructure of the specimen prepared by SPS plus HIP is more homogeneous, and the grain size is smaller than that prepared by vacuum sintering plus HIP. The WC-10Co ultrafine cemented carbide consolidated by SPS plus HIP can reach a relative density of 99.4%, and the transverse rupture strength （TRS） is higher than 3540 MPa, the Rockwell A hardness （HRA） is higher than 92.8, the average grain size is smaller than 300 nm, and the WC-10Co ultrafine cemented carbide with excellent properties is achieved. The specimen prepared by SPS with HIP has better properties and microstructure than that prepared by vacuum sintering with HIP.     

Banach代数中的行列式理论

探讨了 Banach 代数中的行列式理论.给出了具有单位元的迹 Banach 代数具有行列式的充要条件.     

FMS中加工质量故障预报的新方法

对引起加工质量故障的原因进行了研究,建立了用于加工中心加工质量故障分析的与/或故障树,提出了隐加工质量故障(FMQF)的概念和由·FMQF 找出制造系统故障的决策树方法.本文在模糊理论基础上,提出了隐加工质量故障识别的新方法,用这种方法可以根据控制图的变化进行设备状态估计.基于以上研究,建立了可用于柔性制造系统隐加工质量故障预测和预报的专家系统.