郑州大学研究生毕业论文 - 图文

学 校 代 码 10459 学号或申请号 Z201040272 密 级

专业硕士学位论文

粉末冶金法制备SiCw/AZ91复合材料研究

作 者 姓 名： 陈小伟 导 师 姓 名：赵红亮 教授 专业学位名称：材料工程

培 养 院 系：材料科学与工程学院 完 成 时 间：2013年5月

A thesis(dissertation) submitted to

Zhengzhou University for the degree of Master（doctor）

Research on SiCw/AZ91 composites with Powder

Metallurgical Method

By: Xiaowei Chen

Supervisor: Prof. Hongliang Zhao

Materials Engineering

School of Materials Science and Engineering

May 2013

原创性声明

本人郑重声明：所呈交的学位论文，是本人在导师的指导下，独立进行研究所取得的成果。除文中已经注明引用的内容外，本论文不包含任何其他个人或集体已经发表或撰写过的科研成果。对本文的研究作出重要贡献的个人和集体，均已在文中以明确方式标明。本声明的法律责任由本人承担。

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本人在导师指导下完成的论文及相关的职务作品，知识产权归属郑州大学。根据郑州大学有关保留、使用学位论文的规定，同意学校保留或向国家有关部门或机构送交论文的复印件和电子版，允许论文被查阅和借阅；本人授权郑州大学可以将本学位论文的全部或部分编入有关数据库进行检索，可以采用影印、缩印或者其他复制手段保存论文和汇编本学位论文。本人离校后发表、使用学位论文或与该学位论文直接相关的学术论文或成果时，第一署名单位仍然为郑州大学。保密论文在解密后应遵守此规定。

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摘 要

摘要

镁具有密度低、比强度和比刚度高、阻尼性能好、电磁屏蔽能力强及可回收等有点，被誉为“21世纪最具发展潜力的绿色工程材料”，近年来，有关镁合金的研究成为材料学者重点研究课题之一。

本文采用粉末冶金法，制备了以AZ91镁合金为基体、碳化硅晶须为增强体的镁基复合材料，研究了SiC晶须的分散处理方法，分析对比了碳化硅晶须对复合材料显微硬度、拉伸性能及摩擦磨损性能的影响。

SiC晶须在质量分数为1%的硅烷偶联剂(KH550)-无水乙醇分散溶液中分散后，SiC晶须团聚现象明显减轻，效果好于在焦磷酸钠(SPP)水溶液和吐温80(Tween80)-无水乙醇中分散，经分散处理后的SiC晶须增强AZ91镁合金复合材料具有较好的性能。

复合材料的制备采用真空热压烧结工艺，先经15KN、20s冷压后在真空热压烧结机中热压烧结，通过分析测试表明，经过550℃、30KN、300s烧结，具有较好的组织和性能。

制备的SiC晶须增强复合材料的抗拉强度较低，仅为52.92MPa，材料表现为脆性断裂；显微硬度有显著提高，达到95HV0.1，比粉末冶金发法制备的AZ91基体材料硬度提高了33.3%。

摩擦磨损实验结果表明，SiCw/AZ91复合材料的磨损主要表现为脆性材料的磨粒磨损，经分散处理后的SiCw/AZ91复合材料伴随着部分粘着磨损，磨屑较少，磨痕较浅，基体与SiCw结合紧密，耐磨性较好，与粉末冶金法制备的AZ91基体材料相比，加入20%的SiC晶须后材料的摩擦系数提高了29.6%。

关键词：SiCw；粉末冶金；分散剂；镁基复合材料；性能

I

Abstract

Abstract

Magnesium alloy has the advantages of light-weight, high strength/weight ratio, high stiffness / weight ratio, high damping property and electromagnetism shielding property and so on. It is regarded as the most promising green material of the 21st century. In recent years, it is one of important research fields on magnesium alloy for materials scholars.

Powder metallurgy method was used to fabricate SiCw reinforced AZ91 matrix composites in this research. The disperse modes of SiCw was studied. The hardness, tensile strength and frictional wear of acquired composites was analyzed respectively.

SiCw was dispersed better in 1wt.% silane coupling agent ( KH550) - absolute ethyl ethanol solution than 0.5g / L sodium pyrophosphate ( SPP ) aqueous solution and 5% Tween 80( Tween80) – absolute ethyl ethanol solution. The reasonable properties were obtained after dispersing in 1wt.% silane coupling agent ( KH550) - absolute ethyl ethanol solution.

The composite materials were prepared in a vacuum hot pressing sintering. The results indicate that it is reasonable to sinter composites in 550℃, 30KN and 300s.

The composites are brittle so that their tensile performance is not very well, only 52.92Mpa. The hardness was improved obviously with the highest micrhardness of 95HV0.1. It is higer 33.3% than AZ91 matix.

The main wear mechanism of the matrix AZ91 is abrasive wear and a little adhesive wear and oxidative wear. The main wear mechanism of the no-diapersed 20%SiCw/AZ91 is abrasive wear, the ware quantity is the maximum. The main wear mechanism of the diapersed 20% SiCw/AZ91 is abrasive wear and the adhesive ware, and the the ware quantity is little, the matrix and the SiCw combines closely, and it has the best hardness and the friction and wear properties.

Keywords: SiCw; Powder metallurgy; Dispersant; Magnesium matrix composites; Property

II

目 录

目 录

摘要···························································································································Ⅰ Abstract·························································································Ⅱ 1绪论···························································································1

1.1 镁及镁合金··········································································1

1.1.1 镁的性质和用途····························································1 1.1.2 镁合金的种类及用途···················`··································1 1.2 镁合金强韧化方法·································································2 1.2.1 固溶强化·····································································2 1.2.2 沉淀(析出)强化·····························································3 1.2.3 弥散强化·····································································3 1.2.4 细晶强化·····································································3 1.2.5 复合强化·····································································4 1.3 镁基复合材料制备方法···························································4 1.3.1 粉末冶金法··································································4 1.3.2 搅拌铸造法···································································5 1.2.3 熔体浸透法···································································5 1.3.4 喷射沉积法··································································5 1.3.5 原位反应自生法····························································5 1.4 镁基复合材料合金元素及增强相···············································6

1.4.1 复合材料合金元素·························································6 1.4.2 镁基复合材料常用增强相················································7 1.5 课题的提出及主要研究内容······················································9 1.5.1 课题的提出··································································9 1.5.2 本课题的研究内容·························································9

2试验方法及分析手段··································································10

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2.1 复合材料的成分设计·····························································10 2.1.1 基体材料的选择···························································10 2.1.2 增强相的选择·······························································10 2.2 实验设备及化学试剂······························································11 2.2.1 实验设备·····································································11 2.2.2 化学试剂·····································································12 2.3 试样制备···········································································12 2.3.1 晶须分散处理······························································12 2.3.2 配粉···········································································13

2.3.3 混料··········································································14 2.3.4 球磨·········································································14 2.3.5热压烧结试样································································15 2.4 微观分析·········································································17 2.4.1 SEM分析····································································17 2.4.2 EDS分析····································································18 2.5 试样密度测试····································································18 2.6性能测试·········································································19

2.6.1 显微硬度测试······························································19 2.6.2 摩擦磨损性能测试····················································19 2.6.3 拉伸性能测试··························································20

3 SiC晶须分散研究···························································21

3.1 SiC晶须原始形貌···································································21 3.2 SiC晶须分散试验····························································22

3.2.1焦磷酸钠分散处理··························································22 3.2.2吐温80分散处理···············································23 3.2.3硅烷偶联剂分散处理················································23

3.3 本章小结···········································································25

4 SiCw/AZ91复合材料制备工艺的优化··········································26

4.1 球磨工艺的确定·······························································26

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4.2 压力工艺参数的确定····························································27 4.2.1 预压工艺参数确定·························································27 4.2.2烧结压力的确定·····························································27 4.3 烧结工艺的确定····································································29

4.3.1 烧结温度对试样密度的影响············································29 4.3.2 温度对粉末冶金法制备的AZ91基体材料组织形貌的影·······31 4.4 粉末冶金烧结过程分析···························································32 4.5 本章小结·············································································34

5 SiCw/AZ91复合材料的性能·······················································35

5.1 复合材料的显微硬度············································································35 5.2 复合材料的拉伸性能·····························································36 5.3 复合材料摩擦磨损性能·························································37 5.4 复合材料磨损微观形貌分析·····················································41 5.4.1 AZ91基体复合材料的磨损形貌·········································41

5.4.2 SiCw(未处理)/AZ91复合材料的磨损形貌···························44 5.4.3 SiCw(分散处理)/AZ91复合材料的磨损形貌························46 5.5 本章小结······································································································49

6主 要 结 论·······························································································50 参考文献······························································································51 致谢·················································································································55 个人简历 在学期间发表的论文与研究成果···············································56

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图和附表清单

图1.1 合金固溶强化机制····················································································3 图1.2 合金沉淀强化机制····················································································3 图1.3 合金弥散强化···························································································3 图1.4 Mg-Al二元相图························································································6 图1.5 Mg-Al-Zn合金的可铸性············································································7 图2.1 SiC晶须SEM照片及EDS分析···································································11 图2.2 研究技术路线·······················································································12 图2.3 真空球磨示意图·····················································································14 图2.4 四孔圆柱型模具图··················································································15 图2.5 摩擦试样模具图·····················································································16 图2.6 拉伸试样模具图·····················································································16 图2.7 真空热压烧结示意图··············································································17 图2.8 摩擦磨损性能测试试样············································································19 图3.1 SiC晶须SEM照片····················································································21 图3.2 经SPP处理后的SiC晶须形貌···································································22 图3.3 经Tween80处理后的SiC晶须形貌····························································23 图3.4 经KH550处理后的SiC晶须形貌·······························································24 图4.1 球磨后混合粉末SEM照片·······································································26 图4.2 压制压力与压坯密度关系图····································································28 图4.3 试样烧结工艺·························································································29 图4.4 烧结温度与密度关系曲线·······································································30 图4.5 1#试样显微组织······················································································32 图4.6 球形颗粒的烧结模型··············································································33 图4.7 液相烧结过程示意图··············································································33 图5.1 实验材料温度-硬度关系图······································································36 图5.2 烧结温度-磨损量关系图··········································································37 图5.3 AZ91 基体粉末试样的摩擦系数—时间曲线图·········································38 图5.4 AZ91+SiCw(未处理)试样在不同烧结温度下的摩擦系数····························39 图5.5 AZ91+SiCw(已处理)试样在不同烧结温度下的摩擦系数····························40 图5.6 不同烧结温度下试样的摩擦系数·····························································41 图5.7 AZ91基体复合材料的磨损形貌································································42 图5.8 镁合金基体表面EDS分析········································································42 图5.9 不同烧结温度下AZ91基体的磨损形貌·····················································43 图5.10 SiCw(未处理)/AZ91复合材料试样磨损形貌··········································44

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图5.11 SiCw(未处理)/AZ91复合材料试样磨损表面EDS分析·······························44 图5.12 不同烧结温度下SiCw(未处理)/AZ91复合材料磨损形貌··························46 图5.13 2＃和3＃粉末经550℃烧结试样磨损后微观形貌·········································48图5.15 SiCW/AZ91（分散处理）复合材料微观磨损形貌···········································48 表1.1 镁的主要物理性质····················································································1 表2.1 材料成分表······························································································10 表2.2 基体粉末规格·························································································10 表4.1 不同压力下压坯的密度···········································································28 表4.2 烧结工艺参数·························································································29 表4.3 不同温度下烧结试样的密度····································································30

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