磨削硬质合金用金属结合剂金刚石砂轮的性能影响因素

硬质合金具有硬度高、强度好、耐腐蚀和耐磨损的特点,采用传统方法难以满足精密及超精密加工的技术要求。文中研究人造金刚石的品种、粒度、浓度和金属结合剂成分等对金刚石砂轮磨削性能的影响,结果表明：在相同浓度下,粗粒度砂轮具有较高的磨削效率,随着磨粒粒度减小,加工表面质量得到改善,但砂轮尖角保形性先提高后减小;结合剂中加入强碳化合物形成元素和控制结合剂中脆硬相含量有助于提高砂轮磨削性能。     

烧结温度对Ti-Al金属间化合物黏结剂金刚石磨块力学性能和磨削性能的影响

用金属间化合物作为黏结剂的金刚石砂轮在磨削蓝宝石、碳化硅等领域应用广泛。黏结剂与金刚石之间的结合状态直接影响金刚石砂轮的力学和磨削性能。为了研究黏结剂和金刚石的界面结合情况,采用热压法制备Ti-Al金属间化合物黏结剂金刚石磨块,通过多种材料表征方法和摩擦磨损实验研究黏结剂与金刚石之间的界面结合状态和磨块的磨削性能。结果表明：经热压后黏结剂中生成了Ti-Al金属间化合物,且Al在金刚石表面富集从而提高黏结剂对金刚石颗粒的把持力。当烧结温度为900℃时,黏结剂对金刚石颗粒的把持力最高,磨块的力学性能和磨削性能最优,强度和硬度(HRB)最大,分别为160.48 MPa和114.4,磨削蓝宝石的磨耗比为22.3,蓝宝石表面粗糙度为1.37μm。但随着温度的进一步升高,黏结剂的过度氧化会降低磨块的磨削性能。     

工程陶瓷的磨削钻孔及表面形成机理

结合工程陶瓷的加工特性,采用特定组份的铜基结合剂烧结金刚石钻头对其进行孔加工试验研究.结合剂体积分数为48%Cu、30%Co、6%Ni、5%WC、5%Ti、4%Sn、2%Cr.根据烧结金刚石钻头的磨削加工特点,导出了唇面单颗金刚石磨粒的平均载荷的计算公式;在此基础上,结合陶瓷磨削表面的扫描电镜观察,分析了金刚石钻头磨削钻孔的陶瓷材料去除机理.结果表明,在试验条件下,陶瓷材料虽然以脆性断裂去除为主,但也有部分材料发生塑性变形去除.     

溶胶-原位凝胶法制备金刚石/LZAS系陶瓷结合剂砂轮的结构与性能

以硝酸盐溶液、磷酸铵溶液、Si O2溶胶和金刚石颗粒制成混合料浆,经快速凝胶及干燥后,在850℃/1.5 h条件下烧结,得到金刚石/陶瓷结合剂复合体,通过对其微观结构以及表面粗糙度、抗弯强度和孔隙率等性能进行表征,研究混合料浆中的固相含量对金刚石/复合氧化物陶瓷复合体结构与性能的影响。结果表明:Si O2-Al2O3-Zn O-Na2O-Li2O-P2O5复合氧化物陶瓷结合剂的晶化程度高,晶型完整;随料浆中固含量增加,金刚石/陶瓷复合体的孔隙率先降低后升高,而抗弯强度则先升高后降低,当固含量(体积分数)为60%时,砂轮的孔隙率和抗弯强度分别达到最小值(26.2%)和最大值(69 MPa)。与传统粉末压制法制备的金刚石/复合陶瓷结合剂砂轮相比,采用溶胶-凝胶原位法制备的砂轮,结构均匀,抗弯强度和孔隙率分别提高约40.5%和34.8%,磨削加工的硬质合金工件表面无较深划痕,工件表面粗糙度为0.049μm。     

稀土对微粉金刚石磨具使用性能影响的研究

本文通过添加稀土元素，探讨了稀土在改善微粉金刚石—铜锡合金复合材料的烧结性质、提高其使用性能方面的作用。实验结果显示，由于稀土的加入使得磨具表面结合剂明显得到细化，金刚石与结合剂界面结合状态大大改善，保证了磨具工作过程中金刚石微粉的有效出刃和正常工作，从而有效的保证了陶瓷的高效、低粗糙度磨削加工     

镍合金对铸铁短纤维烧结特性的影响

研究了镍合金对铸铁短纤维烧结体组织与烧结特性的影响。含有低熔点镍合金的铸铁短纤维在1100℃烧结时,压坯中可以产生液相,促进镍、铬、硼等合金元素向铸铁中扩散。随镍合金含量增加,铸铁短纤维烧结体的显微组织由铁素体+珠光体向马氏体+奥氏体转变,同时烧结体发生膨胀,孔隙增多。分析了烧结体组织转变及产生膨胀的原因。     

磷含量对铸铁短纤维烧结体组织和性能的影响

研究了合金元素磷对铸铁短纤维烧结体显微组织和性能的影响，结果表明，磷可显著提高铸铁短纤维烧结体的密度、致密化系数，压溃强度和硬变，烧结机理随磷，铜含量的增加逐渐由固相烧结＋瞬态液相烧结转变为液相烧结。     

镀Ni金刚石与铜基结合剂间把持力的提高方法和机理分析

为了提高金刚石与金属结合剂间的把持力, 将镀Ni金刚石在1050℃下处理1 h, 然后用浓硝酸清洗金刚石表面, 最后采用真空热压烧结制备铜基结合剂金刚石样条。用扫描电子显微镜观察高温处理前后金刚石镀层表面形貌, 通过铜基结合剂样条的抗弯强度来评价金刚石与铜基结合剂间的结合力。用X射线衍射仪分析高温处理后镀层与金刚石间的物相。结果表明: 镀Ni金刚石经1050℃处理1 h后, 镀层基本上保持完整, 金刚石表面变粗糙; 铜基结合剂金刚石样条的抗弯强度从未镀金刚石的759 MPa增加到镀Ni金刚石的791 MPa, 再增加到高温处理镀Ni金刚石的833 MPa, 说明金刚石与铜基结合剂间把持力得到有效提高。     

孔隙率对超薄金刚石切割砂轮性能的影响

研究了超薄金刚石切割砂轮中孔隙率对金属结合剂的影响,以及不同压力和温度对金刚石砂轮孔隙率的影响。实验结果表明,压力对砂轮孔隙率的贡献明显高于温度,温度对孔隙率的贡献主要表现在孔隙的形貌上。本实验用数学方法推导了超薄金刚石切割砂轮孔隙率与其抗弯强度的关系,为超薄金刚石切割砂轮的配方和工艺设计提供了数据基础和实践经验。     

金刚石修整笔的选用及BD型金刚石修整笔的特点

磨削是机械加工的一个重要工序,在大多数情况下也是最后一道工序。通过磨削,保证机械零件获得要求的精度和光洁度。为此,除要求机床有足够的精度外,对砂轮也有一定的要求,因此必须对砂轮进行修整。修整的目的有三点:1.使砂轮具有一定的形状;2.使砂轮具有一定的精度;3.使砂轮保持锋利。在磨削过程中,砂轮的砂粒被磨损而变钝,同时砂粒之间的孔隙也被堵塞,造成排屑困难。所以,砂轮在使用一段时间后应进行修整,以除去工作面的钝化层。目前我国应用的砂轮修整工具主要有以下三种:金刚石刀:采用质量优良的等级金刚石,以专用     

Wear resistance of chromium-containing matrices of diamond drilling tools

The paper examines the wear rate in friction of copper-impregnated samples produced by pressing of VK6 powder with chromium additions. The test is conducted on a cast iron disk in the presence of a wet SiC powder and on a diamond wheel without cooling. It is shown that higher chromium content insignificantly increases the sample wear rate in friction with the cast iron disk. At the same time, the wear rate abruptly decreases for the diamond wheel. The hardness of the samples does not significantly change with increasing chromium content to 6 wt.%.     

中速磨煤机磨辊的选材和应用

根据广钢热电厂中速磨煤机磨辊使用寿命较低的情况 ,试制了一种新型高硬度高铬铸铁磨辊 ,该铸铁抗磨损性能优异 ,磨辊使用寿命有较大幅度的提高     

The Properties and Performance of Cast Iron Grinding Media

Cast iron balls have been used for decades as a grinding media in all types of grinding applications. Early applications of cast iron grinding balls in mineral processing operations were disastrous due to spalling and premature breakage. Better control and understanding of a high chromium cast iron metallurgical system have led to the use of high chromium cast iron balls in all types of grinding. This paper reviews the wear properties of cast iron grinding media materials during dry and wet grinding conditions. The media wear mechanisms and the factors influencing the grinding ball wear during grinding are discussed, giving special importance to the corrosion and abrasion properties of cast iron media materials.     

Microstructure, Impact Fatigue Resistance and Impact Wear Resistance of Wear Resistant Low Cr-Si Cast Iron

Wear parts are greatly consumed in metallurgi-cal industry,fire power stations and cement works.The consumption of grinding balls and lining platesmay be the greatestunder such impactabrasive wearconditions.In China,annual consumption of ballsand plates is close to 1× 10 6 t.Therefore,develop-ing a new material for impact wear conditions is veryimportant.　　 The martensitic high chromium cast iron(WCr= 15 % ) is widely studied and used as wear resis-tance material[1— 8] ,especially for ma…     

短圆柱型磨矿介质用于新疆星塔金矿二段磨矿的试验研究

以新疆星塔金矿矿石为研究对象,采用短圆柱型磨矿介质(铸铁段)和钢球对二段磨矿效果进行了对比磨矿试验,最终确定了选矿厂Ф2.1 m×3.5 m溢流型球磨机的初装介质尺寸组成m(35×40)∶m(30×35)∶m(25×30)=30∶30∶40。在相同的磨矿条件下,铸铁段Ⅰ的磨矿产品中+0.15 mm过粗粒级、-0.01 mm过粉碎粒级产率比最佳钢球配比的分别低0.77百分点、0.15百分点,-0.15~+0.01 mm易选粒级和-0.074 mm产率比最佳钢球配比的分别高0.92百分点、0.54百分点。工业试验结果表明:采用铸铁段后磨矿细度增加4.90百分点,金回收率提高0.77百分点,金精矿品位增加13.0%;铸铁段因其独特的优势可以作为细磨介质在选矿厂推广应用。     

采用钨渣生产合金铸铁磨球

高铬铸铁磨球由于生产成本高，熔铸工艺复杂，参数控制要求严格，成品率低使其推广应用受到限制，采用复合变质方法，开发工艺简单，成本低的钨渣合金铸铁磨球是一种有效的途径，其材质性能可以满足使用的要求。     

Effect of Microstructure on Impact Fatigue Resistance and Impact Wear Resistance of Medium Cr-Si Cast Iron

 A great amount of iron grinding balls in tube mills have been consumed. Under this impact abrasive wear working condition, the failure of wear resistant alloying white irons grinding balls is mainly caused by fatigue spalling. The impact wear resistance of martensitic high chromium cast iron (Cr of 15%) is not high sometimes, but its cost is not low. Thus, medium Cr Si wear resistant cast iron is recommended. The influence of the iron on impact fatigue resistance and impact wear resistance is pronounced. Ball on ball impact fatigue test and high stress impact wear test of the grinding balls have been carried out. The results show that the impact fatigue resistance (IFR) and impact wear resistance (IWR) of medium Cr Si cast iron are superior to those of martensitic high chromium cast iron (Cr of 15%). The main reasons are that (1) the stress in medium Cr Si cast iron is released in the as cast state; (2) the matrix is fine pearlite with better toughness and plasticity; (3) the pearlite is more stable compared with a retained austenite under repeated impact load and less phase transformation can take place; (4) high silicon content improves the morphology of eutectic carbide; (5) there is no secondary carbide which results in less crack sources. All these factors are beneficial to improvement of impact fatigue spalling resistance. The eutectic carbide M7C3 is the main constituent to resist wear.     

聚酰亚胺树脂金刚石砂轮的制造和应用

介绍了聚酰亚胺树脂的特性和金刚石树脂砂轮的制造工艺，并对其进行了磨削试验。结果表明，用聚酰亚胺树脂粉制造的金刚石磨具，具有优良的耐磨性能，取得了满意的实际应用效果。