Low‐Cost Silicon Nitride from β‐Silicon Nitride Powder and by Low‐Temperature Sintering

Abstract

Aiming to manufacture low‐cost silicon nitride components, a low‐cost β powder was chosen as a raw powder and low‐temperature sintering at 1550–1600°C under atmospheric pressure nitrogen was carried out. The silicon nitride from β powder with 5 wt% Y2O3 and 5 wt% MgAl2O4 additives and sintered at 1600°C for 8 h was successfully densified, and it exhibited moderate strength and toughness of 553 MPa ± 22 and 3.5 MPa m1/2, respectively. The results indicate that the low‐temperature sintering of the low‐cost β powder has a potential to reduce cost of components.

Advanced ceramics and coatings for erosion‐related applications in mineral and oil and gas production: A technical review

“…Although these ceramics are produced as rather small components, they should be considered for the machinery and rotating equipment. Among the mentioned materials, the highest potential of Si 3 N 4 ‐based ceramics is related to their high fracture toughness, which is comparable with PSZ, combined with high strength, Young's modulus and hardness and to a possibility to fire these ceramics at rather low temperatures 167–169 . The Si 3 N 4 ‐based ceramics with Y 2 O 3 –Al 2 O 3 dopants sintered in air are a good option for this application as it also has a homogeneous microcrystalline structure formed by β‐Si 3 N 4 with crystalline–glassy grain boundaries and high mechanical properties, and its process can be considered an economical route with no use of a controlled atmosphere for sintering 170 …”

“…Among the mentioned materials, the highest potential of Si 3 N 4 -based ceramics is related to their high fracture toughness, which is comparable with PSZ, combined with high strength, Young's modulus and hardness and to a possibility to fire these ceramics at rather low temperatures. [167][168][169] The Si 3 N 4 -based ceramics with Y 2 O 3 -Al 2 O 3 dopants sintered in air are a good option for this application as it also has a homogeneous microcrystalline structure formed by β-Si 3 N 4 with crystalline-glassy grain boundaries and high mechanical properties, and its process can be considered an economical route with no use of a controlled atmosphere for sintering. 170 For the heterogeneous SiC-based ceramics with large (1-2 mm) SiC grains, Rockwell hardness and strength are similar despite the presence or absence of Si 3 N 4 ingredient in the starting composition, which is defined by these large grains.…”

Preparation of Si3N4 ceramic based on digital light processing 3D printing and precursor infiltration and pyrolysis

“…Molding technology was an important factor to determine the properties of ceramic products and was also a key link in the preparation of complex shape parts. How to manufacture highly reliable and defect‐free ceramics with complex shapes at an acceptable cost was a great challenge 5–9 …”

“…How to manufacture highly reliable and defect-free ceramics with complex shapes at an acceptable cost was a great challenge. [5][6][7][8][9] The appearance of 3D printing (additive manufacturing) provides the possibility for the preparation of complex structure ceramic materials. 3D printing technology mainly uses computers to model parts and then directly "prints" ceramic parts with complex shapes without molds.…”

Rare Earth Oxides on Properties of Pressureless Sintered Si3N4 Ceramics

“…无 机 材 料 学 报 第 32 卷 氮化硅陶瓷具有优异的力学性能以及良好的抗 热震性能, 被广泛应用于结构陶瓷领域 [1][2] 。 1995 年 Haggerty 和 Lightfoot 等 [3][4] 发现氮化硅陶瓷的理论 热导率可达到 320 W/(m•K), 这引起了广泛关注。 目 前氮化硅陶瓷热导率最高可达 177 W/(m•K), 由 Zhou 等 [5] 采用反应重烧结技术(SRBSN)并以 Y 2 O 3 和 MgO 作为烧结助剂制备得到, 同时该材料具有 高韧性和强度, 能够取代 AlN 陶瓷材料作为新一代 基板材料。 另外, 研究发现添加稀土氧化物结合氧化镁作 为烧结助剂, 采用气压烧结技术能够制备出高性 能、致密氮化硅陶瓷材料 [6][7] 。但是该技术通常需要 在高温和高氮压条件下长时间烧结, 生产成本极高, 而且长时间保温会使材料的力学性能下降, 也无法 满足苛刻环境的应用需求。因此, 人们利用氮化硅 陶瓷优异的力学性能, 通过降低材料的厚度, 来降 低整体热阻, 从而降低对氮化硅热导率的严苛要 求。这样就使得采用常压烧结技术制备氮化硅陶瓷 材料成为可能。Lee 等 [8][9] 通过合成 LiYO 2 作为烧结 助剂, 在 1600℃保温 8 h 得到致密的氮化硅陶瓷材 料, 但是热导率仅为 26~38 W/(m•K)。Yang 等 [10][11] 通过引入 Ce 2 O 3 -MgO 在 1800℃烧结后, 获得抗弯 强度为 948 MPa 的氮化硅陶瓷样品。Kondo 等 [12] 通过采用 β-Si 3 N 4 粉体作为原料, 引入氧化钇和镁铝 尖晶石, 1600℃保温 8 h 后得到抗弯强度为 553 MPa 的致密氮化硅陶瓷。近期, Guo 等 [13] [14] , 并通过晶型转 变以及晶粒的进一步生长促进材料的烧结和致密化。 当烧结助剂含量大于8wt%时, 材料的密度随稀 土离子半径的减小而增大, 其中稀土氧化物的详细 数据如表 2 所列。该现象与 Wang 等 [15][16][17][18] 的研究结 表 1 烧结助剂中稀土氧化物和氧化钛质量比 [19]…”