Morphology and deposition rates of TiB2 prepared by chemical vapour deposition of TiCl4 + B2H6 system
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Titanium diboride (TiB2) deposits were obtained on a graphite substrate by chemical vapour deposition using TiCl4, B2H6 and H2 at deposition temperatures (Tdep) of 1323 to 1773 K and total gas pressures (Ptot) of 4 to 40 kPa. B/Ti molar ratio in the source gases [2B2H6/TiCl4(mB/Ti)] was varied from 0.6 to 4. TiB2 plates were prepared at mB/Ti = 0.6 to 2. The deposition rate increased with increasing Tdep. The largest value of the deposition rate was 1.4 × 10−7 m sec−1 (0.5 mmh−1) at Tdep = 1773 K, Ptot =40 kPa and mB/Ti = 0.6. The activation energies for the formation of CVD−TiB2 plate were 41 to 51 kJ mol−1. These values suggest that the diffusion of gaseous species through the boundary layer is a rate-determining process.
KeywordsDeposition Rate TiCl Deposition Temperature B2H6 Titanium Diboride
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