Growth kinetics of titanium borides produced by CRTD-Bor method


Kartal G., Timur S. İ.

SURFACE & COATINGS TECHNOLOGY, cilt.215, ss.440-446, 2013 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 215
  • Basım Tarihi: 2013
  • Doi Numarası: 10.1016/j.surfcoat.2012.08.076
  • Dergi Adı: SURFACE & COATINGS TECHNOLOGY
  • Sayfa Sayıları: ss.440-446

Özet

In this study, a new bonding method called CRTD-Bor (Cathodic Reduction and Thermal Diffusion based bonding) was applied to titanium in a systematic manner and the effects of bonding process parameters on the morphological and chemical state of boride layers were explored. The presence of both TiB and TiB2 phases was confirmed by the X-ray diffraction technique. The cross-sectional examination of bonded titanium verified the boride layers consisted of a homogeneous TiB2 phase on the top and TiB whiskers toward the substrate. Moreover, the growth kinetics of the TiB2 layers forming on titanium substrates was investigated during CRTD-bor which was performed at a constant current density of 200 mA/cm(2) in a borax based electrolyte at temperatures ranging from 900 to 1100 degrees C for periods of 15 to 120 min. The rate of the TiB2 layer formation was found to have a parabolic character at all applied process temperatures. The activation energy (Q) and the pre-exponential factor (K-o) of the TiB2 layer were determined as 189.9 kJ/mol and 4.66 x 10(-7)m(2) s(-1), respectively. The specific empirical equation that can be used to estimate the thickness of the TiB2 layers (d(TiB2)) for the conditions explored in the study is d(TiB2) = 682.67 root exp(-22833/T)t 1173 K <= T <= 1373 K; 200 mA/cm(2). (C) 2012 Elsevier B.V. All rights reserved.