CVD金刚石涂层拉丝模温度场数值分析

衬底温度是热丝化学气相沉积(HFCVD)制备金刚石薄膜的重要参数之一,在拉丝模表面沉积CVD金刚石涂层时,均匀的衬底温度场显得尤为重要.对HFCVD系统中制备CVD金刚石涂层时拉丝模衬底温度场进行数值分析,得到了拉丝模温度场的分布和热丝参数对衬底温度场的影响规律,为CVD金刚石涂层拉丝模的制备提供重要指导.     

CVD金刚石薄膜涂层铜线拉丝模的制备与应用

提高金刚石薄膜的表面质量和附着力是实现CVD金刚石涂层在耐磨器件领域中广泛应用的关键因素.本文通过优化沉积工艺参数,采用直拉丝化学气相沉积法在WC- Co硬质合金拉丝模内孔表面沉积金刚石薄膜.检测了该涂层的表面形貌、薄膜质量以及表面粗糙度,并把所制备的CVD金刚石薄膜涂层拉丝模具在拉拔铜线材生产线上进行了应用试验,结果...     

金刚石薄膜磁性研磨抛光研究

表面粗糙度是影响金刚石薄膜广泛应用的主要因素,选择一种合适的抛光方式可以大幅度降低表面粗糙度,以加速其商业化应用的进程。文中针对内孔金刚石薄膜,提出了一种新的抛光方法——磁性研磨抛光。实验结果表明,可有效除去薄膜晶粒外缘的尖角,而且不会造成涂层的损伤,不影响涂层附着力,是一种温和的抛光方法,可以达到比较理想的抛光效果,采用磁性研磨抛光的金刚石涂层铜杆拉丝模,工作寿命比硬质合金模具提高8-10倍,满足了铜杆拉丝对模具内孔表面光洁度的更高要求。     

聚晶金刚石拉丝模拉拔过程的计算仿真

采用ABAQUS有限元分析软件对太阳能硅片切割丝拉制用聚晶金刚石拉丝模拉拔过程进行了运动仿真,根据拉丝模结构对称性的特点,选择1/2模型进行分析,并对模套的上下表面施加全约束来模拟拉丝的实际状况。通过计算获得了切割丝轴向应力分布图及所受最大轴向拉应力随时间变化曲线和聚晶金刚石拉丝模等效应力分布图及所受的等效应力曲线,并进行了分析总结。最后得出在拉拔加工过程中聚晶金刚石模芯所受的最大等效应力为6474MPa,从而为拉丝模模芯材料的选择提供了一定的理论依据。     

金刚石涂层刀具

金刚石涂层刀具,具有金刚石的硬度、化学隐定性和低的摩擦系数。金刚石涂层广泛用于刀具、拉丝模、耐磨件、轴承座圈等,其价格将会不断降低。金刚石涂层刀具将从车削进一步用于铣削和间断切削,同时提高生产率。 1.PCD用于铝加工 聚晶金刚石(PCD)刀具广泛用于加工有色金属和难加工耐磨材料。 PCD是烧结合成的,PCD刀具的缺点在于只有单个切削刃,尺寸受限制,无断屑槽,一旦损环,经济损失较大。目前,PCD刀具广泛用于铝件加工,如汽车发动机、缸体、缸盖和变速箱。 从70年代初,GE超硬材料分部已给工具制造商提供PCD片,帮助用户用PCD和CBN取代硬质合金和氮化硅。80年代初,所有发动机和变速箱厂的铝件精加工都使用聚晶金刚石,最近8～9年已用于粗加工和间断切削,其寿命为硬质合金的20～50倍。     

De Beers公司生产出高品级大颗粒人造金刚石单晶体

<正> 据De Beers公司C·Phaal博士介绍,该公司在改进制造金刚石高压/高温合成工艺方面取得了突破性的进展,现已能经济地生产出最大为4克拉(0.8克)的高品级金刚石单晶。据认为这已达到了目前经济合理地生产金刚石单晶的极限。这种大颗粒金刚石单晶是在特殊设备上制造的,并已能批量生产;如今主要用作拉丝模的坯料。采用激光可将这种金刚石单晶切成所需形状(如片状),还可用其制造单晶金刚石刀具、砂轮修正器和手术刀等。此外该公司在金刚石CVD涂层工艺方面也取得显著成效,应用范围不断扩大,将给硬质合金,甚至多晶金刚石市场带来压力。     

金刚石拉丝模的失效分析

用扫描电子正微镜观察20多个失效金刚石拉丝模的模口形貌。拉丝过程中金刚石模子的失效是由金刚石沿(111)面解理引起的。两个相邻的模子装配时轴线偏斜,在以后拉丝过程中,模子破坏就会严重,以致失效、报废。离子注入后的拉丝模可以改善它的使用寿命。     

以SiC过渡层为预处理工艺的金刚石涂层硬质合金微径铣刀研究

研究了采用强电流直流伸展电弧等离子体CVD技术,以SiC过渡层为预处理工艺,直径为0.8mm的微径铣刀上纳米金刚石涂层的制备。通过铣削6063DL31铝合金并与未涂层的微径铣刀进行对比,验证SiC过渡层+金刚石涂层微径铣刀的切削性能。结果表明,SiC过渡层可以有效降低Co对金刚石涂层沉积的不利影响,改善金刚石涂层的附着力,同时,铝合金铣削试验表明,金刚石涂层微径铣刀可以有效降低切屑的黏结和毛刺的形成,并且显著降低加工工件的表面粗糙度;因此,薄SiC过渡层可以作为预处理工艺应用于微径铣刀上金刚石涂层的制备。     

微/纳米CVD金刚石涂层的制备

使用热丝化学气相沉积(HFCVD)装置,在以WC - CO硬质合金为衬底,采用调节涂层生长参数,制备出性能优良的微/纳米金刚石涂层.用SEM,AFM,Raman表征微观结构和表面品质.采用压痕法评估涂层的结合性能,并与微米金刚石涂层、纳米金刚石涂层进行比较.结果显示,当生长气压由3.3 kPa降为1.0 kPa时,底层的微米级晶粒逐渐被上层纳米级晶粒覆盖,并且涂层表面显露出纳米金刚石涂层特性.在结合性能实验中也指出,微/纳米金刚石涂层的结合性能比纳米金刚石涂层要优异.     

金刚石涂层刀具干铣削TC4切削性能研究

金刚石涂层刀具被广泛应用于硬质难加工材料的加工过程中,可降低切削力、增加刀具寿命。以TC4合金试样为例,研究了由化学气相沉积(CVD)法制备的金刚石涂层刀具的切削性能,并以普通硬质合金刀具作为参照对象。实验结果表明:金刚石涂层铣刀切削性能并不优于硬质合金刀具。在临界温度下,石墨化和氧化会导致金刚石涂层刀具快速失效。     

CVD金刚石涂层拉拔模的制备

针对拉制铝管用尼龙模具寿命短和硬质合金模具粘铝的问题,采用微波等离子体CVD法在硬质合金拉拔模内孔壁涂覆金刚石薄膜。通过设计一个特殊支撑结构,引导等离子体进入拉拔模内孔,可实现在内孔8mm深度范围一次沉积出金刚石膜。现场拉拔试验表明,金刚石涂层模拉制的铝管光洁度介于尼龙模和硬质合金模之间,可满足使用要求。     

STUDY ON COATING MECHANISM OF DIAMOND FILM ON CUTTING TOOL AND ITS APPLICATION

0 INTRODUCT[ONDiamond is a kind Of excellent cutting tool material for cutting non-fermus metal and nonmetallicmaterials. Because of the limited supply and high cost of natural diamond it has been mainly used forspecial aPPlications Where no other tools can Perform satisfactorily.The study of dePOsition of diamond film on cutting tools and its wide aPPlications began in 1980.Great Progress has been made at the same time. The [ypical principles used in coated-cutting tool are thehacrow…     

基于有限元模拟的铜包铝线拉拔参数优化

为研究拉拔参数对铜包铝线质量的影响,运用有限元方法对金刚石涂层拉拔模具拉拔铜包铝线的过程进行了模拟仿真,研究了拉拔过程中模具的应力分布情况,分析了压缩率对铜包铝线残余应力分布均匀性的影响规律。利用正交实验法研究了拉拔参数(工作锥半角α,定径带长度L,过渡圆弧半径R,压缩率β)对铜包铝线尺寸精度和残余应力分布均匀性的影响,获得了最佳拉拔参数(α=6°,L=4.5 mm,R=3 mm,β=1.82%)和各因素对分析指标的影响规律。并在此基础上对优化方案进行了模拟,结果证明了正交实验对拉拔参数优化的有效性,对金刚石涂层拉拔模具的设计及高质量铜包铝线的拉制有重要的指导意义。     

高性能CVD金刚石薄膜涂层刀具的制备和试验研究

采用电子增强热丝EACVD法,以WC-Co硬质合金刀具为衬底制备金刚石涂层刀具,研究了提高涂层附着力的衬底预处理新方法,探讨了抑制Co催石墨化作用的有效措施,提出了改善金刚石薄膜表面粗糙度CVD后处理新工艺。研究结果表明,采用了Ar-H2微波等离子体刻蚀脱碳预处理方法对于提高金刚石薄膜涂层的附着力有明显效果,添加适量粘结促进剂,可有效地抑制CVD沉积过程中钴向表层扩散引起的催石墨化作用。采用分步沉积新工艺是减小金刚石薄膜表面粗糙度的有效方法。所制备的高附着力和低粗糙度的金刚石薄膜涂层刀具切削性能明显改善,对实现高效高精度切削加工具有十分重要的意义。     

非晶金刚石膜在高速钢丝锥上的应用

利用过滤阴极真空电弧离子镀膜机 (JM 1型非晶金刚石镀膜机 )在高速钢试件和丝锥上沉积 150～2 0 0nm的非晶金刚石膜 ,对该镀膜丝锥进行摩擦系数、膜 /基结合力、耐磨性以及丝锥效能试验 ,并在多个用户厂进行应用考核。试验结果表明 ,非晶金刚石膜对钢的摩擦系数为 0 0 92～ 0 0 98,膜 /基结合力 (临界载荷 )为 17 65～2 0 2 7N ,耐磨寿命比高速钢基体提高 10 6～ 3 19倍 ,镀膜丝锥寿命提高 2 46～ 5 6倍。实用考核表明 ,镀膜丝锥在加工有色金属、钢、铸铁机件的应用中 ,分别提高丝锥寿命 0 67～ 4 56倍     

Friction and Wear Performance of Boron Doped,Undoped Microcrystalline and Fine Grained Composite Diamond Films

Chemical vapor deposition(CVD) diamond films have attracted more attentions due to their excellent mechanical properties. Whereas as-fabricated traditional diamond films in the previous studies don’t have enough adhesion or surface smoothness, which seriously impact their friction and wear performance, and thus limit their applications under extremely harsh conditions. A boron doped, undoped microcrystalline and fine grained composite diamond(BD-UM-FGCD) film is fabricated by a three-step method adopting hot filament CVD(HFCVD) method in the present study, presenting outstanding comprehensive performance, including the good adhesion between the substrate and the underlying boron doped diamond(BDD) layer, the extremely high hardness of the middle undoped microcrystalline diamond(UMCD) layer, as well as the low surface roughness and favorable polished convenience of the surface fine grained diamond(FGD) layer. The friction and wear behavior of this composite film sliding against low-carbon steel and silicon nitride balls are studied on a ball-on-plate rotational friction tester. Besides, its wear rate is further evaluated under a severer condition using an inner-hole polishing apparatus, with low-carbon steel wire as the counterpart. The test results show that the BD-UM-FGCD film performs very small friction coefficient and great friction behavior owing to its high surface smoothness, and meanwhile it also has excellent wear resistance because of the relatively high hardness of the surface FGD film and the extremely high hardness of the middle UMCD film. Moreover, under the industrial conditions for producing low-carbon steel wires, this composite film can sufficiently prolong the working lifetime of the drawing dies and improve their application effects. This research develops a novel composite diamond films owning great comprehensive properties, which have great potentials as protecting coatings on working surfaces of the wear-resistant and anti-frictional components.     

Approach for Polishing Diamond Coated Complicated Cutting Tool: Abrasive Flow Machining(AFM)

Lower surface roughness and sharper cutting edge are beneficial for improving the machining quality of the cut?ting tool, while coatings often deteriorate them. Focusing on the diamond coated WC?Co milling cutter, the abrasive flow machining(AFM) is selected for reducing the surface roughness and sharpening the cutting edge. Comparative cutting tests are conducted on di erent types of coated cutters before and after AFM, as well as uncoated WC?Co one, demonstrating that the boron?doped microcrystalline and undoped fine?grained composite diamond coated cutter after the AFM(AFM?BDM?UFGCD) is a good choice for the finish milling of the 6063 Al alloy in the present case, because it shows favorable machining quality close to the uncoated one, but much prolonged tool lifetime. Besides, compared with the micro?sized diamond films, it is much more convenient and e cient to finish the BDM?UFGCD coated cutter covered by nano?sized diamond grains, and resharpen its cutting edge by the AFM, owing to the lower initial surface roughness and hardness. Moreover, the boron incorporation and micro?sized grains in the underly?ing layer can enhance the film?substrate adhesion, avoid the rapid film removal in the machining process, and thus maximize the tool life(1040 m, four times more than the uncoated one). In general, the AFM is firstly proposed and discussed for post?processing the diamond coated complicated cutting tools, which is proved to be feasible for improving the cutting performance     

CVD金刚石涂层刀具切削性能的试验研究

金刚石薄膜具有高硬度、低摩擦系数、高耐磨性和高导热性能。文中通过用金刚石薄膜涂层刀具对含硅量不同的硅铝合金进行干切削试验,探讨其切削性能。