Effect of M-ZrO2 on Sintering Behavior and Thermal Shock Resistance of Dense Cr2O3 Material

2011 ◽  
Vol 199-200 ◽  
pp. 1928-1931 ◽  
Author(s):  
Hong Ji Yin ◽  
Tao Zhang ◽  
Ai Jun Wu ◽  
Jin Xiang Wang
Keyword(s):  
Polyvinyl Alcohol ◽  
Oxygen Partial Pressure ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Room Temperature ◽  
Cold Isostatic Pressing ◽  
Sintering Behavior ◽  
Quenching Effect ◽  
Material Sample ◽  
Shock Resistance

The samples were prepared using Cr2O3 micropowder, TiO2 micropowder and m-ZrO2 micropowder as main starting material, polyvinyl alcohol as binder, by a series of processes such as pulping, spraying granulation, machine moulding and cold isostatic pressing, and sintering at 1 500°С for 3 h in nitrogen protected atmosphere furnace (oxygen partial pressure was 10 Pa). Then thermal shock resistance of the samples was tested by wind quenching. Effect of m-ZrO2 (2%-5% in mass) on sintering behavior and thermal shock resistance of Cr2O3 material was investigated. The results show that m-ZrO2 can accelerate the sintering of Cr2O3 material, but excess 2 wt% m-ZrO2 doesn’t work; m-ZrO2 can obviously improve thermal shock resistance of Cr2O3 material, sample containing 3 wt% m-ZrO2 has 34 wind quenching cycles from 1 150°С to room temperature, and sample without m-ZrO2 only has 11 cycles.

Effect of Aluminium Sol on Microstructure and Properties of Corundum-Mullite Ceramic

2007 ◽  
Vol 336-338 ◽  
pp. 1333-1336
Author(s):  
Ben Jun Cheng ◽  
Xing Zhong Guo ◽  
Li Li ◽  
Dong Yun Li
Keyword(s):  
High Temperature ◽  
Polyvinyl Alcohol ◽  
Bulk Density ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Room Temperature ◽  
Mullite Ceramic ◽  
Microstructure And Properties ◽  
Shock Resistance ◽  
Mullite Ceramics

The effect of aluminium sol on the properties and microstructure of corundum-mullite ceramics was investigated. The sample with 1.5 wt% aluminium sol possessed higher room-temperature and high-temperature strengths, while the sample with 3 wt% aluminium sol had higher bulk density, lower apparent porosity and better thermal shock resistance. Aluminium sol not only acts as a binder instead of some polyvinyl alcohol (PVA), but also reacts with silica to form mullite, which improves the properties and microstructure of the ceramics by increasing corundum and mullite phases.

Influence of Silicon Nitride on Properties of Corundum Based Castable

2013 ◽  
Vol 634-638 ◽  
pp. 2358-2361
Author(s):  
Jun Cong Wei ◽  
Li Rong Yang
Keyword(s):  
Electron Microscopy ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Cold Strength ◽  
X Ray ◽  
Refractory Castables ◽  
Shock Resistance ◽  
Scanning Electron

The effects of Si3N4 addition on the room temperature physical properties and thermal shock resistance properties of corundum based refractory castables were investigated using brown corundum, white corundum and alumina micropowder as the starting materials and pure calcium aluminate as a binder. The phase composition, microstructure, mechanical properties of corundum based castables were investigated by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that as the increase in Si3N4 addition, the bulk density decreased and apparent porosity increased, the cold strength deduced. However, the residual strength rate increased. That is, the thermal shock resistance was improved. This is because even though the introduction of Si3N4 inhibited the sintering of material and deduced the compactness, microcracks were produced in the materials due to a difference in thermal expansion coefficient. So the thermal shock resistance of corundum based castable was improved.

scholarly journals Titania Effect on Sintering behavior of Alumina

2009 ◽  
Vol 6 (4) ◽  
pp. 770-774
Author(s):  
Baghdad Science Journal
Keyword(s):  
Water Absorption ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Sintering Temperature ◽  
Shrinkage Porosity ◽  
Sintering Behavior ◽  
Pure Alumina ◽  
Titania Powder ◽  
Laboratory Results ◽  
Shock Resistance

The sintering behavior of Alumina was investigated by adding TiO2. The addition of TiO2 lowered the sintering temperature of the Alumina compared with those of pure Alumina. The result suggests that TiO2 acts as an activator for sintering of Alumina. Water absorption, apparent porosity and density were examined for both pure and TiO2 added to Alumina samples. The variations of sintering behavior were discussed in terms of shrinkage, porosity, water absorption and density. Thermal shock resistance was also examined. In term of this work, the way of improving the thermal shock resistance in oxide- based materials by adding reactive Titania powder to the Alumina samples. The laboratory results showed an improvement in thermal shock resistance property of the products which open the horizon of development of the final products.

scholarly journals Hot Pressed Silcon Nitride for Gas Turbine Applications

1972 ◽  
Author(s):  
M. L. Torti ◽  
G. Q. Weaver ◽  
D. W. Richerson
Keyword(s):  
Elevated Temperature ◽  
Silicon Nitride ◽  
Thermal Shock ◽  
Gas Turbine ◽  
Thermal Shock Resistance ◽  
Room Temperature ◽  
Promising Candidate ◽  
Shock Resistance ◽  
Room Temperature Strength

The high strengths now attainable with hot pressed silicon nitride combined with its good oxidation and thermal shock resistance make it a most promising candidate for advanced gas turbine hot components. This form of silicon nitride has flexural strengths of 110,000 psi at room temperature and 60,000 psi at 1200 C. A recent experimental version of the system has exhibited room temperature strength of 145,000 psi and elevated temperature (1200 C) strength of 100,000 psi. This may be the highest strength reported on any material at this elevated temperature.

Microstructure and Thermal Shock Resistance of LaPO4-ZrO2

2008 ◽  
Vol 368-372 ◽  
pp. 1633-1635 ◽  
Author(s):  
Zhong Qiu Li ◽  
Jia Chen Liu ◽  
Shun Li ◽  
Bing Zhou ◽  
Wei Jing
Keyword(s):  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Room Temperature ◽  
Slip Casting ◽  
Strength Degradation ◽  
Bending Test ◽  
Three Point Bending ◽  
Shock Resistance

LaPO4-ZrO2 composites were prepared by slip casting and pressureless-sintered in air. The effects of LaPO4 addition on microstructure and thermal shock resistance were addressed. The thermal shock resistance of the composites was evaluated by air quenching and a subsequent three-point bending test to determine the strength degradation. Comparisons were made with results from parallel experiments conducted using a ZrO2 ceramic without LaPO4 additions. The reference ZrO2 ceramic showed the expected substantial strength losses when thermally quenched from 470oC above room temperature. By contrast, the LaPO4-ZrO2 ceramics, while displaying reduced strength relative to the reference ZrO2 ceramics, exhibited minimal strength degradation under severe thermal shock conditions.

Study on Thermal Shock Resistance of Insulated Metal Substrate

2005 ◽  
Vol 475-479 ◽  
pp. 1737-1742
Author(s):  
Liquan Guo ◽  
Yang Liu ◽  
Ju Sheng Ma
Keyword(s):  
Thermal Conductivity ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Room Temperature ◽  
Metal Substrate ◽  
Anodic Film ◽  
Excellent Performance ◽  
Insulating Layer ◽  
Shock Resistance ◽  
Thermal Shocks

Anodizing technique was applied to prepare insulated metal substrates (IMS) for BGA packaging. “Ideal” IMS used anodic film of aluminum as the insulating layer instead of epoxy, which led to higher thermal conductivity. But the thermal shock resistance of IMS is poor because of the great difference of thermal expansion coefficient between aluminum and its anodic film. In this study, different anodizing processes of aluminum were analyzed. The parameters, which can affect the thermal shock resistance of IMS, especially the surface temperature of Al substrate, were studied. The anodic film obtained with the optimized parameters of anodizing process had excellent performance, such as the resistivity was over 1013Ω·cm, the breakdown voltage was higher than 600V, and the most important thing was that it could resist thermal shocks between room temperature and 300°C. Then BGA packaging was successfully performed based on this IMS.

The Effect of Temperature on the Course of Refractory Castables Cracking

2013 ◽  
Vol 592-593 ◽  
pp. 769-772
Author(s):  
Renata Suwak ◽  
Józef Wojsa
Keyword(s):  
Crack Propagation ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Simultaneous Presentation ◽  
Effect Of Temperature ◽  
Internal Stresses ◽  
Refractory Castables ◽  
The Matrix ◽  
Material Sample ◽  
Shock Resistance

Factors determining the durability of a material include among others its thermal shock resistance, as a non-homogenous temperature field may trigger the formation and propagation of cracks. To evaluate thermal shock resistance by means of one of the resistance criteria: the Rst or R4 parameter, it is necessary to know the work of fracture (γWOF), which is determined in a cracking test. Technical testing conditions influence the recording of crack propagation in a material sample. Ordinary and refractory castables are a group of materials in which the effect of temperature on the course of their cracking is among others related to the presence of deformations, internal stresses and cracks. Tests were performed for mullite, andalusite and boxite doped chromia castables, having known phase compositions, for which the temperature of liquid phase appearance in the matrix was calculated. A considerable increase in the value of castables γWOF at 900°C was noted compared to the values at 300°C and 600°C. In the group of the examined castables the highest γWOF value was obtained for andalusite castable. The applied methods of testing enabled simultaneous presentation of crack propagation in terms of energy (load vs. deformation) and kinetics (load vs. time).

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