Microstructure and high temperature 4-point bending creep of sol–gel derived mullite ceramics

Abstract

Four-point bending creep behavior of mullite ceramics with monomodal and bimodal distribution of grain sizes was studied in the temperature range of 1320-1400 • C under the stresses between 40 and 160 MPa. Mullite ceramic with bimodal grain size distribution was prepared using aluminum nitrate nonahydrate as alumina precursor. When ␥-Al 2 O 3 or boehmite were used as alumina precursors, mullite grains are equiaxial with mean particle size of 0.6 m for the former and 1.3 m for the latter alumina precursor. The highest creep rate exhibited the sample with monomodal morphology and grains in size of 0.6 m, which is about one order of magnitude greater than that for the monomodal morphology but with grains in size of 1.3 m. The highest activation energy for creep (Q = 742 ± 33 kJ/mol) exhibits mullite with equiaxial grains of 1.3 m, whereas for sample with smaller equiaxial grains the activation energy is much smaller and similar to mullite ceramics with bimodal grain morphology. Intergranular fracture is predominant near the tension surface, while transgranular more planar fracture is predominant near the compression surface zone.

Tribological behavior of carbon nanotube/aluminosilicate composites prepared through TEOS/boehmite catalyst sol–gel and CVD process

“…Mullite is known to be an advanced high temperature ceramic due to its remarkable physical and chemical properties [1,2]. Many methods are available for mullite synthesis.…”

Effect of Surface Roughness on the Determination of the Creep Properties of Material by Using Three Points Bending Creep Test

“…Based on the results of Hollenberg et al, Chuang, Krause and Chuang [7] and Chen and Chuang [8] investigated the relationships among neutral axis position, creep parameters and the bending moment. Recently, Chuang et al [11] proposed multi-axial constitutive equations in a power-law creep form based on asymmetric creep responses under uniaxial creep. In addition, some other researchers have also studied the high temperature materials creep properties using the bending creep test by the finite element method or combining the test with numerical technique such as Lin et al [9], Ivankovic et al [10], Lim et al [11], Dusza et al [12] and so on.…”

“…Recently, Chuang et al [11] proposed multi-axial constitutive equations in a power-law creep form based on asymmetric creep responses under uniaxial creep. In addition, some other researchers have also studied the high temperature materials creep properties using the bending creep test by the finite element method or combining the test with numerical technique such as Lin et al [9], Ivankovic et al [10], Lim et al [11], Dusza et al [12] and so on. But the usual bending creep fixture in use is three-point bending test fixture or four-point bending test fixture [8][9][10][11][12][13][14].…”

Solgel‐Processed Mullite Coating—A Review

“…1 Coating is a process to make a layer having thickness generally from submicrometer to nanometer range of a substance spread over a surface. [12][13][14][15][16][17] Owing to these important qualities, mullite are widely used in the production of refractory material, optical and electrical components, electronic packaging, biological processes, [18][19][20][21][22] etc. Although there are a number of techniques such as vapor deposition, plasma-assisted/ionbeam-assisted deposition, and atomic layer deposition to coat planar surfaces, solgel process has the unique feature for complex shape coating in nanometer to micrometer scale.…”