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.

The Thermal Shock Resistance of Mg-PSZ/LaPO4 Ceramics

2013 ◽  
Vol 785-786 ◽  
pp. 187-190
Author(s):  
Zhong Qiu Li ◽  
Li Jie Ci ◽  
Tie Cheng Feng ◽  
Shao Yan Zhang
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Strength Degradation ◽  
Water Quenching ◽  
Bending Test ◽  
Three Point Bending ◽  
Shock Resistance ◽  
Thermal Shock Behavior

The mechanical properties and thermal shock behavior of Mg-PSZ/LaPO4 ceramics was investigated. The thermal shock resistance of the materials was evaluated by water quenching and a subsequent three-point bending test to determine the flexural strength degradation. Mg-PSZ/15LaPO4 composite showed a higher thermal shock resistance and behaved as a typical refractory. The calculation of thermal shock resistance parameters for the composites and the monolith had indicated possible explanations for the differences in thermal shock behavior.

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.

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.

scholarly journals Comparative Study of the Thermal Shock Resistance of an Industrial Tableware Porcelain

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Habib Sahlaoui ◽  
Kamel Makhlouf ◽  
Habib Sidhom
Keyword(s):  
Low Temperature ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Mechanical Resistance ◽  
Firing Cycle ◽  
Bending Tests ◽  
Three Point Bending ◽  
Shock Resistance ◽  
Silica Ratio ◽  
Thermal Shocks

The effect of the glazed layer and firing conditions (temperature and duration) on the thermal shocks behavior of tableware porcelains has been studied. Two types of glazed layers and three firing conditions, used industrially in the commercial porcelains manufacture, are used in this investigation. Repeated thermal shock tests showed that the glazed layer with higher alumina/silica ratio is more resistant to thermal shocks and that the slow firing cycle, even at a relatively low temperature, is very beneficial for the thermal shock resistance of the porcelain matrix. Three-point bending tests showed that the crazing phenomenon, which affects the glazed layers as well as the porcelain matrix, does not affect significantly the mechanical resistance of these materials.

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.

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.

scholarly journals Evaluation of Functionally Graded Ceramic Crucible for Induction Melting of Titanium Based Alloys

2012 ◽  
Vol 730-732 ◽  
pp. 769-774 ◽  
Author(s):  
Fernando Gomes ◽  
Joaquim Barbosa ◽  
Carlos Silva Ribeiro
Keyword(s):  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Slip Casting ◽  
Casting Process ◽  
Functionally Graded ◽  
Induction Melting ◽  
Chemical Contamination ◽  
Melting Crucible ◽  
Residual Elements ◽  
Shock Resistance

During the last years a very significant effort to develop a melting crucible for induction melting of Ti based alloys at competitive cost has been carried out by many researchers, where the authors are included. Results obtained so far have shown that no material accomplishes the melting crucibles two main demands: inertness facing titanium alloys and suitable/enough thermal-shock resistance. Until now, yttrium and calcium oxides were those materials that performed best on what concerns to thermodynamic stability. However, in both cases, crucibles thermal-shock resistance was very poor, and there are references to crucibles that cracked during melting. Besides, calcium oxide reveals manipulation problems, due to its high higroscopicity. This paper concerns to the evaluation of zircon based crucibles with Y2O3 inner layer for induction melting of TiAl based alloys. A novel multi layered crucible production technique based in a centrifugally assisted slip casting process followed by a sintering operation is described, and results concerning to crucibles porosity and wall composition and morphology are presented. Crucibles obtained in different processing conditions were used to melt a Ti48Al alloy which was poured in graphite moulds. Experimental results include alloy chemical contamination with residual elements, mainly yttrium and oxygen, microhardness measurement and the presence of yttrium oxide and zircon inclusions in the cast samples. Results concerning to the crucibles behaviour are also presented with particular attention to cracks development. The Y2O3 crucible layer was found to suffer some erosion and be slightly dissolved by the molten alloy and the extent of those phenomena depends on the porosity of the layer surface, for fixed experimental melting 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.

scholarly journals Comparing the influence of different kinds of zirconia on properties and microstructure of Al2O3 ceramics

2016 ◽  
Vol 23 (4) ◽  
pp. 407-412
Author(s):  
Wenfeng Li ◽  
Suping Li ◽  
Xiangchong Zhong
Keyword(s):  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Room Temperature ◽  
Yttria Stabilized Zirconia ◽  
Modulus Of Rupture ◽  
Monoclinic Zirconia ◽  
Stabilized Zirconia ◽  
Microstructure Characteristics ◽  
Shock Resistance ◽  
Room Temperature Strength

AbstractThis paper compared the influence of fused zirconia-corundum (AZ40), monoclinic zirconia (m-ZrO2), and 3 mol% yttria-stabilized zirconia (3Y-ZrO2) on physical properties at room temperature, hot modulus of rupture, and thermal shock resistance of Al2O3 ceramics, and their relationships with microstructure changes were investigated. It was found that m-ZrO2 or 3Y-ZrO2 addition promoted the process of sintering densification and enhanced the room temperature strength and the hot modulus of rupture of Al2O3 ceramics, and the effect of the latter was more distinct, while those of the sample with AZ40 addition decreased. In addition, the three kinds of ZrO2 were beneficial to improving the thermal shock resistance of Al2O3 ceramics. All these changes had close relationships with the changes of corresponding microstructure characteristics (including distribution of particles, degree of contact between crystals, grain boundary solid solution, microcrack density) and phase composition.

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