International Journal of Minerals, Metallurgy and Materials
Volume 19, Number 8, Aug 2012, Page 757
DOI: 10.1007/s12613-012-0624-0
Corresponding author: Xiao-lei Li E-mail: lxlei@tju.edu.cn
© University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg 2012
Phase analysis and thermal conductivity of in situ O′-sialon/β-Si
3
N
4
composites
Xiao-lei Li, Xiao-liang Chen, Hui-ming Ji, Xiao-hong Sun, and Ling-ge Zhao
School of Material Science and Engineering, Key Laboratory for Advanced and Machining Technology (Ministry of Education), Tianjin University, Tianjin 300072,
China
(Received: 8 June 2011; revised: 9 November 2011; accepted: 11 November 2011)
Abstract: Typical O′-sialon-based ceramics, with a formula of Si
2−x
Al
x
O
1+x
N
2−x
, where x was set as 0.25, were fabricated by in-situ synthesis.
Si
3
N
4
, Al
2
O
3
, and SiO
2
powders were used as raw materials, and MgO and Y
2
O
3
were added as sintering additives. All the samples were sin-
tered at different temperatures under a nitrogen pressure of 0.25-0.30 MPa, and their microstructure, phase content, and thermal conductivity
were evaluated. The effects of O′-sialon and β-Si
3
N
4
on the thermal conductivity were analyzed by numerical calculation in detail. In the case
of the similar porosity, the thermal conductivity of O′-sialon-based ceramics decreased with the ratio of O′-sialon/β-Si
3
N
4
increasing. When
the ratio was 12, the thermal conductivity of O′-sialon ceramics sintered at 1360°C was 1.197 W⋅m
−1
⋅K
−1
.
Keywords: ceramic materials; sintering; phase composition; thermal conductivity; numerical calculation
1. Introduction
The solid solubility of Al
2
O
3
in the Si
3
N
4
lattice led to a
major family of oxynitride ceramics, i.e. the sialons [1].
Sialon ceramics are used widely for high-temperature indus-
trial, automotive, and aerospace applications. As an impor-
tant member of the sialon family, O′-sialon has shown great
research prospects for its excellent behavior at high tem-
perature [2]. Since the first discovery in the early 1970s
[3-4], considerable advancements have been made in the
past decades, especially in the aspect of oxidation resistance
[2, 5-9]. Recently, it is reported that the room thermal con-
ductivity of β-Si
3
N
4
ceramics varies from 10 to 162
W⋅m
−1
⋅K
−1
, which depends on the purity of raw materials,
the type and content of sintering additives, and the condi-
tions of the sintering process [10-16]. However, details of
these factors influencing the thermal conductivity of
O′-sialon, which play an important role in engineering ap-
plications, are rarely reported. In some special applications,
a lower thermal conductivity is expected for O′-sialon ce-
ramics, for example, high-temperature heatproof. This paper
focuses on the methods to reduce the thermal conductivity
of O′-sialon multiphase ceramics from the aspects of micro-
structure and phase composition.
2. Experimental
High-purity α-Si
3
N
4
, SiO
2
, and α-Al
2
O
3
powders were
used as raw materials. Y
2
O
3
and MgO (purity 99wt%) were
added as sintering additives. The O′-sialon composition is
commonly described as Si
2−x
Al
x
O
1+x
N
2−x
, with x varying
from 0 to 0.3. In this study, the value of x in all the samples
is set as 0.25. α-Al
2
O
3
powders with different specific sur-
face areas were employed: 1# α-Al
2
O
3
(specific surface area
3 m
2
/g) and 2# α-Al
2
O
3
(specific surface area 8 m
2
/g). The
initial composition of the samples is shown in Table 1.
Table 1. Initial composition of samples wt%
Sample α-Si
3
N
4
SiO
2
Y
2
O
3
α-Al
2
O
3
type α-Al
2
O
3
Z1 59.5 25.4 2.5 1# 12.6
Z2 58.0 24.7 5.0 1# 12.3
Z3 58.0 24.7 5.0 2# 12.3
The starting powders were prepared by ball milling; disks
of 32-mm diameter and 5-mm thickness were formed by
mold pressing and the succedent isostatic press of 100 MPa.
All the samples were sintered at different temperatures in a
furnace with a flowing nitrogen atmosphere. Crystalline
下载后可阅读完整内容，剩余4页未读，立即下载
weixin_38529397
- 粉丝: 4
- 资源: 938
我的内容管理
展开
最新资源
- Unity UGUI性能优化实战：UGUI_BatchDemo示例
- Java实现小游戏飞翔的小鸟教程分享
- Ant Design 4.16.8：企业级React组件库的最新更新
- Windows下MongoDB的安装教程与步骤
- 婚庆公司响应式网站模板源码下载
- 高端旅行推荐：官网模板及移动响应式网页设计
- Java基础教程：类与接口的实现与应用
- 高级版照片排版软件功能介绍与操作指南
- 精品黑色插画设计师作品展示网页模板
- 蓝色互联网科技企业Bootstrap网站模板下载
- MQTTFX 1.7.1版：Windows平台最强Mqtt客户端体验
- 黑色摄影主题响应式网站模板设计案例
- 扁平化风格商业旅游网站模板设计
- 绿色留学H5模板：科研教育机构官网解决方案
- Linux环境下EMQX安装全流程指导
- 可爱卡通儿童APP官网模板_复古绿色动画设计
资源上传下载、课程学习等过程中有任何疑问或建议，欢迎提出宝贵意见哦~我们会及时处理！
点击此处反馈
