Influence of the Microstructure on Macro/Micro versus Nanohardness of SiC Ceramics

2014 ◽  
Vol 606 ◽  
pp. 197-200 ◽  
Author(s):  
Alexandra Kovalčíková ◽  
Ján Dusza ◽  
Pavol Šajgalík
Keyword(s):  
Silicon Carbide ◽  
Elastic Modulus ◽  
Liquid Phase ◽  
Grain Growth ◽  
Depth Sensing ◽  
Sic Ceramics ◽  
Peak Loads ◽  
Heat Treated ◽  
Indentation Tests ◽  
Sintered Silicon

The influence of microstructural variations on the macro/microhardness, nanohardness and Young`s modulus of liquid phase sintered silicon carbide (LPS SiC) has been observed. In order to modify the microstructures some samples were further heat treated at 1850°C for 5 hours to promote grain growth. The depth-sensing indentation tests of SiC materials were performed at several peak loads in the range 10-400 mN. For a better assessment, the indentation values of hardness and Young`s modulus modulus of SiC matrix were also compared to the hardness and Elastic modulus of individual SiC grains. The comparison of macro/micro and nanohardness showed that nanohardness was significantly higher, generally by 6-7 GPa. The nanohardness of individual plate-like SiC grains was around 2 GPa higher than nanohardness of SiC matrix.

Effects of rare-earth oxide and alumina additives on thermal conductivity of liquid-phase-sintered silicon carbide

2003 ◽  
Vol 18 (8) ◽  
pp. 1854-1862 ◽  
Author(s):  
You Zhou ◽  
Kiyoshi Hirao ◽  
Yukihiko Yamauchi ◽  
Shuzo Kanzaki
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Rare Earth ◽  
Liquid Phase ◽  
Point Defects ◽  
Rare Earth Oxide ◽  
Low Oxygen ◽  
Sic Ceramics ◽  
Sintered Silicon ◽  
Thermal Conductivities

SiC ceramics were prepared from a β–SiC powder doped with two different sintering additives—a mixture of La2O3and Y2O3and a mixture of Al2O3and Y2O3—by hot pressing and annealing. Their microstructures, phase compositions, lattice oxygen contents, and thermal conductivities were evaluated. The SiC doped with rare-earth oxides attained thermal conductivities in excess of 200 W/(m K); however, the SiC doped with additives containing alumina had thermal conductivities lower than 71 W/(m K). The high thermal conductivity of the rare-earth-oxide-doped SiC was attributed to the low oxygen content in SiC lattice, high SiC–SiC contiguity, and lack of β– to α–SiC polytypic transformation. The low thermal conductivity of the alumina-doped SiC was attributed to the point defects resulting from the dissolution of Al2O3into SiC lattice and the occurrence of polytypic transformation.

Microstructural Variations in SiC Ceramics Sintered with AlN-Y2O3

2006 ◽  
Vol 530-531 ◽  
pp. 532-537 ◽  
Author(s):  
Kurt Strecker ◽  
Claudinei dos Santos ◽  
M.J. Bondioli ◽  
Michael J. Hoffmann
Keyword(s):  
Weight Loss ◽  
Liquid Phase ◽  
Grain Growth ◽  
Liquid Phase Sintering ◽  
Sic Ceramics ◽  
N2 Atmosphere ◽  
Heat Treated

In this work, SiC ceramics were prepared by liquid phase sintering using 10 wt.% of AlN and Y2O3 mixtures in the proportion of 4:1 and 2:3 as additives Sintering was done in a graphite resistance heated furnace at 2080oC under 0.2 MPa N2 atmosphere for 1h. Part of the samples was further heat-treated at 2000oC for 4h to allow grain growth. The microstructures of the sintered samples were analyzed using polished and plasma etched surfaces. Furthermore, relative densities, weight loss during sintering and SiC-polytype distributions are reported.

Influence of Microstructure on Tribological Properties and Nanohardness of Silicon Carbide Ceramics

2015 ◽  
Vol 662 ◽  
pp. 55-58 ◽  
Author(s):  
Alexandra Kovalčíková ◽  
Ján Balko ◽  
Ján Dusza
Keyword(s):  
Silicon Carbide ◽  
Tribological Properties ◽  
Sliding Friction ◽  
Depth Sensing ◽  
Globular Microstructure ◽  
Heat Treated ◽  
Indentation Tests ◽  
Order Of Magnitude ◽  
Carbide Ceramics ◽  
Silicon Carbide Ceramics

The influence of microstructural variations on the tribological properties and nanohardness of liquid phase sintered silicon carbide (LPS SiC) has been observed. In order to modify the microstructures samples were further heat treated at 1650°C and 1850°C for 5 hours to promote grain growth. The depth-sensing indentation tests of SiC materials were performed at several peak loads in the range 10-400 mN. The pin-on-flat dry sliding friction and wear experiments have been made on SiC ceramics in contact with Al2O3 ceramic ball at 10-50 N loads in an ambient environment. The nanohardness of samples with plate-like microstructure was about 34 GPa i.e. 3 GPa higher than nanohardness of SiC with fine globular microstructure. The SiC materials with coarser plate-like microstructure had similar COF (0.4-0.55) and better wear resistance (one order of magnitude at normal forces 10-20N) than SiC materials with fine globular microstructure.

Effect of Weight Loss on Liquid-Phase-Sintered Silicon Carbide

2005 ◽  
Vol 80 (4) ◽  
pp. 1047-1052 ◽  
Author(s):  
Tor Grande ◽  
Hkon Sommerset ◽  
Eirik Hagen ◽  
Kjell Wiik ◽  
Mari-Ann Einarsrud
Keyword(s):  
Silicon Carbide ◽  
Weight Loss ◽  
Liquid Phase ◽  
Sintered Silicon

scholarly journals Analysis of depth-sensing indentation tests with a Knoop indenter

2001 ◽  
Vol 16 (6) ◽  
pp. 1660-1667 ◽  
Author(s):  
L. Riester ◽  
T. J. Bell ◽  
A. C. Fischer-Cripps
Keyword(s):  
Elastic Modulus ◽  
Elastic Recovery ◽  
Indentation Test ◽  
New Method ◽  
Short Axis ◽  
Depth Sensing ◽  
Specimen Material ◽  
Indentation Tests ◽  
Conventional Methods ◽  
Knoop Indenter

The present work shows how data obtained in a depth-sensing indentation test using a Knoop indenter may be analyzed to provide elastic modulus and hardness of the specimen material. The method takes into account the elastic recovery along the direction of the short axis of the residual impression as the indenter is removed. If elastic recovery is not accounted for, the elastic modulus and hardness are overestimated by an amount that depends on the ratio of E/H of the specimen material. The new method of analysis expresses the elastic recovery of the short diagonal of the residual impression into an equivalent face angle for one side of the Knoop indenter. Conventional methods of analysis using this corrected angle provide results for modulus and hardness that are consistent with those obtained with other types of indenters.

Quantitative Phase-Composition Analysis of Liquid-Phase-Sintered Silicon Carbide Using the Rietveld Method

2004 ◽  
Vol 83 (9) ◽  
pp. 2282-2286 ◽  
Author(s):  
Angel L. Ortiz ◽  
Francisco L. Cumbrera ◽  
Florentino Sánchez-Bajo ◽  
Fernando Guiberteau ◽  
Huiwen Xu ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Phase Composition ◽  
Liquid Phase ◽  
Rietveld Method ◽  
Composition Analysis ◽  
Quantitative Phase ◽  
Phase Composition Analysis ◽  
Sintered Silicon
Sign in / Sign up

Export Citation Format

Share Document