金属Al粉对氧化硅基陶瓷型芯的性能及组织的影响

doi:10.15541/jim20180206

摘要/Abstract

摘要：

本工作以石英玻璃粉作为基体材料, 白刚玉粉作为矿化剂, 金属Al粉作为添加剂, 制备了氧化硅基陶瓷型芯。研究了不同含量金属Al粉对氧化硅基陶瓷型芯收缩率、物理性能、显微组织和相组成的影响。研究结果表明, 在型芯烧结过程中, 金属Al粉受热氧化形成Al₂O₃, 伴随着体积膨胀和重量增加, 可以抑制陶瓷型芯的烧结收缩和铸造收缩。Al粉对烧结过程中的方石英析晶无明显抑制作用, 铸造过程中由于型芯骨架结构的松散程度增加, 型芯的高温抗变形能力降低。当铝粉含量为1wt%时, 陶瓷型芯综合性能良好, 三维方向的烧结收缩率分别为0.01%、0.03%、0.03%, 气孔率为28.58%, 挠度为0.57 mm, 抗弯强度为12.1 MPa。制备的陶瓷型芯能够满足高温合金定向凝固需求, 并有望能提高空心涡轮叶片的内腔尺寸精度。

关键词: 氧化硅基陶瓷型芯, 铝粉, 烧结收缩率, 空心叶片

Abstract:

Silica-based ceramic core was produced by fused silica as matrix material, corundum powder as mineralizer, and Al powder as additive. Effects of aluminum powder contents on the ceramic core regarding shrinkage rate, physical performance, and microstructure were investigated. Results showed that through sintering process, aluminum powder was oxidized to alumina, accompanying with volume expansion and weight gain, which reduced sintering and casting shrinkages of silica-based ceramic core. There is no obvious inhibitory effect on devitrification by Al powder in the sintering process. Due to increased looseness of core skeleton structure in the casting process, the high temperature creep deformation increased. The sample with 1wt% Al showed good comprehensive properties, of which three-dimensional direction of sintering shrinkage rate were 0.01%, 0.03%, 0.03%, respectively, and porosity rate, deflection bending strength were 28.58%, 0.57 mm, 12.1 MPa, respectively. All these data demonstrated that the new core materials can meet the requirement of directional solidification and be expected to improve the dimensional accuracy of the hollow turbine blade.

Key words: silica-based ceramic core, Al powder, sintering shrinkage, hollow blade

中图分类号:

TQ174

李鑫,牛书鑫,姚建省,唐定中,曹春晓,闫军浩. 金属Al粉对氧化硅基陶瓷型芯的性能及组织的影响[J]. 无机材料学报, 2019, 34(2): 207-212.

LI Xin, NIU Shu-Xin, YAO Jian-Sheng, TANG Ding-Zhong, CAO Chun-Xiao, YAN Jun-Hao. Effect of Al Powder on Property and Microstructure of Silica-based Ceramic Core[J]. Journal of Inorganic Materials, 2019, 34(2): 207-212.

图/表 11

表1 原材料化学成分及粒度特征

Table 1 Characteristics of fused silica, alumina, and aluminite powder as raw materials

Raw materials	Purity/%	Particle size distribution/μm
Raw materials	Purity/%	D₁₀	D₅₀	D₉₀
Fused silica	≥99.95	7.5	34.4	104.0
Corundum	Al₂O₃≥99.5	3.2	15.9	40.5
Aluminite	≥99.5	-	1-3	-

图1 金属Al粉的SEM照片

Fig. 1 SEM images of Al powders(a) Room temperature; (b) 1100 ℃, 0.5 h

图2 Al粉含量对型芯试样烧结收缩率的影响

Fig. 2 Effect of Al content on sintering shrinkage of ceramic cores

图3 Al粉的差热-失重曲线

Fig. 3 Thermal analysis graphs of Al powder

图4 Al粉含量对型芯试样铸造收缩率的影响

Fig. 4 Effect of Al content on as-casting shrikage of ceramic cores

图5 Al粉含量对型芯的体积密度、显气孔率与抗弯强度的影响

Fig. 5 Flexural strength and apparent porosity results of the ceramic cores with various Al contents

图6 型芯的高温挠度随Al粉含量的变化情况

Fig. 6 Variation of the creep deformation of ceramic core with Al contents

图7 不同含量Al粉浇注后型芯的孔径分布曲线

Fig. 7 Pore size distribution curve of as-casting ceramic core with different Al contents

图8 不同温度热处理Al粉的XRD图谱

Fig. 8 XRD patterns of Al powder heat-treatement at different temperatures

图9 在1200 ℃烧结、不同Al含量陶瓷型芯试样的XRD图谱

Fig. 9 XRD patterns of ceramic cores with different Al contents sintered at 1200 ℃

图10 添加不同含量Al粉的型芯试样SEM照片

Fig. 10 SEM images of sintered core samples with various Al contents(a) 0; (b) 1wt%; (c) 3wt%; (d) 5wt%; (e) High magnification image of 3wt% sample; (f) High magnification image of 5wt% sample

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