Adhesion strength of titanium particles to alumina substrates: A combined cold spray and LIPIT study

• Published in: Surface & coatings technology Vol. 361; pp. 403 - 412
• Main Authors: Imbriglio, S.I., Hassani-Gangaraj, M., Veysset, D., Aghasibeig, M., Gauvin, R., Nelson, K.A., Schuh, C.A., Chromik, R.R.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.03.2019; Elsevier BV
• Subjects: Adhesion strength; Adhesion tests; Adhesive strength; Alumina-Titanium; Aluminum oxide; Bond strength; Bonding strength; Cold; Cold spray; Critical velocity; Deposition; Impact; Impact tests; Impact velocity; Metal/ceramic interface; Morphology; Particle impact; Projectiles; Sintering (powder metallurgy); Substrate morphology; Substrates; Titanium; Velocity; Impact; Impact velocity; Substrate morphology; Cold spray; Metal/ceramic interface; Adhesion strength
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2019.01.071

The cold spray process and laser-induced projectile impact test (LIPIT) are used to deposit Ti powder particles on sintered polycrystalline Al2O3. Whereas LIPIT allows real-time observations of single particle impact and measurement of particle impact velocity, cold spray rapidly and simultaneously deposits particles with a wide range of deposition velocities and sizes. By use of these two techniques, the effect of particle velocity and substrate morphology on adhesion strength of single splats is investigated. The critical velocity for deposition is identified to be approximately 580 m/s for the Ti/Al2O3 system when using LIPIT and particles of 10 μm. Above the critical velocity, flattening ratio (FR) is also evaluated and observed to be linearly dependent on the particle impact velocity. Splat adhesion testing is performed on LIPIT-deposited as well as on cold spray-deposited powder particles to measure adhesion strength. This analysis shows that adhesion strength is highly affected by local substrate surface morphology, where particles bond more weakly to relatively smooth portions of the substrate. Therefore, mechanical bonding plays a significant role in adhesion. Also, adhesion strength decreases with an increase in FR and therefore velocity. This decrease can be associated with fracture of the ceramic substrate and rebound forces. •Ti splats are deposited on sintered polycrystalline Al2O3 by cold spray and LIPIT.•LIPIT revealed that Ti splats begin to bond to Al2O3 at approximately 580 m/s.•Flattening ratio can be used to estimate an effective velocity for single splats.•Adhesion strength is inversely proportional to flattening ratio for cold spray splats.•Areas on the substrate with smaller Al2O3 grains lead to higher adhesion strength.