The special graphite substrate for TaC coating produced by Huajin New Materials Company can highly match the thermal expansion of TaC coating at different temperatures (20-200℃：5.9*10-6/K；20-600℃：6.3*10-6/K；20-1600℃：7.1*10-6/K), perfectly solving the problems of coating cracking and peeling caused by multiple temperature changes, effectively improving the service time of workpieces.
Compared with SiC coated graphite, the new generation of TaC coated graphite has significantly improved high-temperature corrosion resistance, service time, and ability to suppress impurity atom migration. Its operating temperature has been extended from 900-1500 ℃ to a maximum of 2400 ℃, and its application scenarios have expanded from homogeneous/heterogeneous epitaxy of semiconductor single crystals to semiconductor wafer growth (seed crystal holder, guide tube, graphite crucible, guide ring) and other fields. The transformation of coating materials has put forward higher requirements for the thermal expansion coefficient, electrical and chemical stability, surface roughness, mechanical strength, and thermal conductivity of graphite substrates.
When the processing temperature exceeds 2400 ℃ in a highly uniform temperature field, the electrical and chemical stability of Huajin New Material's tantalum carbide coated graphite substrate is significantly improved, and the material homogeneity is significantly improved. The maximum density difference is ≤ 0.01 g/cm, and the resistivity is ≤ 10 μΩ·m.
The raw material of the company's products is ultra-fine particles, and during the heat treatment process, the particles are sintered by fusion and integration, resulting in high densification. The average density reaches 1.92 g/cm³, with an average pore size of ≤0.4 μm and a porosity of ≤12%. Compared with the traditional graphite, our products demonstrate significantly improved surface roughness and machinability. The preparation process is precisely controlled, the microstructure is dense and uniform, the internal defects are significantly reduced. The ultimate external stresses endured are greatly improved, and the flexural strength of the batch products is ≥80 MPa, and the flexural strength of the superior products is ≥85 MPa.
The company's products adopt an ultra-long time heat treatment process, with a complete crystal structure, optimized La and Lc values, an average graphitization degree of ≥ 80%, and a thermal conductivity of ≥ 145 W/m·K.
Mark |
Bulk density（g/cm³) |
Bulk density （10-6/K） |
Resistivity（μΩm） |
Aperture（μm） |
Porosity（%） |
Flexural strength（MPa） |
Thermal conductivity（W/m*K） |
HJ-Ta-1 |
1.93 |
6.3（20～600℃） 7.1（1600℃） |
10-11 |
≤0.4 |
＜12 |
80-85 |
≥120 |
HJ-Ta-2 |
1.95 |
6.3（20～600℃） 7.1（1600℃） |
10 |
≤0.3 |
＜11 |
85-90 |
≥145 |