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Si-doped diamond films with various Si concentrations are deposited on WC-Co substrates using HFCVD method, with the mixture of acetone, tetraethoxysilane (TEOS) and hydrogen as the reactant source. A variety of characterizations, including FE-SEM, AFM, Raman, XRD, surface profilometer and Rockwell indentation, are conducted to systematically investigate the influence of Si incorporation on diamond films. As the Si/C ratio from 0% to 5%, the grain size of as-deposited films decreases from 4 μm to about 50 nm, and the surface roughness reduces from Ra ~ 290 nm to Ra ~ 180 nm. Besides, the intensity ratio of I(111)/I(220) varies from 0.57 to 0, indicating the 〈110〉 preferred orientation of the nanocrystalline structure in the 5% doped diamond films. The silicon doping is beneficial for the formation of non-diamond carbide phases in the films, according to the Raman spectra. Moreover, the film adhesion is also improved with the increase of Si/C ratio.

Diamond films have been deposited on the interior hole surface of cobalt-cemented tungsten carbide (WC–Co) drawing dies from acetone, trimethyl borate (C₃H₉BO₃), tetraethoxysilane (C₈H${}_{20}$O₄Si, TEOS) and hydrogen mixture by hot-filament chemical vapor deposition (HFCVD) method. The structures and quality of as-deposited diamond films are characterized with field-emission scanning electron microscopy (FESEM) and Raman spectroscopy. The abrasion ratio and the adhesive strength of as-deposited diamond films are evaluated by copper wire drawing tests and ultrasonic lapping tests, respectively. The results suggest that diamond films with small grain size and high growth rate can be obtained due to the mutual effects of boron and silicon impurities in the gas phases. The results of ultrasonic lapping tests show that diamond films doped with boron and/or silicon can bear the severe erosion of the large diamond powder. Diamond films peeling off within the reduction zone of the drawing dies cannot be observed after testing of 2h. The abrasion ratio of boron and silicon-added diamond films is five times that of diamond films without any addition. Adding boron and/or silicon in the diamond films is proved to be an efficient way to obtain high-adhesive-strength and high-abrasion-resistance diamond-coated drawing dies.

TiAlN-coated cemented carbide samples were treated using an Nd:YAG laser at different scanning speeds after the physical vapor deposition (PVD) process. The ball-on-disk wear tests in dry friction condition were performed to evaluate the tribological properties of the treated TiAlN coated samples sliding against AISI 316 stainless steel materials. Characterization tests such as instrumented nanoindentation hardness tests and variable depth scratch tests were also carried out to evaluate the mechanical properties as well as the coating adhesiveness of the PVD TiAlN coatings with additional laser treatments. Results showed that the post-laser processing with appropriate input parameters can significantly affect the coating adhesiveness and anti-adhesive wear properties. In this study, the moderate scanning speed (10mm/s) is most effective in minimizing the PVD coating defect, densifying the PVD coating and increasing the critical load of the coatings, resulting in a increase of 32% in critical load of the coatings. Meanwhile, specific attention was paid to the role of post-laser processing in the stable protective layer formation. The adhesion layer of steel materials shows its best adherence to the post-treated TiAlN coating surface in combination with a high mechanical stability, due to a synergistic effect of the improved coating/substrate adhesion and mechanical interlock.

Hydroxyapatite films were formed on various substrates such as 12 mol% ceria-doped tetragonal zirconia (12Ce-TZP), 3 mol% yttria-doped tetragonal zirconia (3Y-TZP), alumina, monetite coated titanium (Ti/CaHPO₄) and calcium titanate coated titanium (Ti/CaTiO₃) via hydrothermal reactions of Ca(edta)^2- and 0.05 M NaH₂PO₄ at initial pH 6 and 160 - 200°C for 0.5- 6 h. Morphology of the film changed depending on the substrate, i.e. hydroxyapatite entirely coated the surfaces of l2Ce-TZP, Ti/CaHPO₄ and Ti/CaTiO₃ plates, but sparsely deposited on 3Y-TZP and Al₂O₃ plates. Film thickness increased with time (ca. 41 and 90μm on 12Ce-TZP for 2 and 6 h, respectively, at pH 6 and 200 °C). Adhesive strength of the film changed depending on the substrate as 12Ce-TZP(28 MPa) > CaTiO₃ coated Ti (22 MPa) > Ti/CaHPO₄ (9 MPa).

In the present study, hydroxyapatite (HAp) was electrophoretically deposited on Ti, Ti6A14V and 316L stainless steel substrates. The effects of sintering temperatures ranging from 875°C to 1000°C on the bonding strength between the HAp coating and metal substrates were investigated. In general, sintering causes decomposition of the HAp coating even at a temperature of 875°C. In the present study, dual HAp coatings were prepared. The use of dual HAp coatings enabled decomposition to be confined to the “undercoat”, while the surface coating remained decomposition free. The bonding strength between the HAp coating and the metal substrates was assessed by shear strength testing, according to ASTM F 1044-87. It was found that the coating on stainless steel sintered at 925°C gave the best result among the three substrates, 25 MPa of adhesive strength. The high adhesive strength of stainless steel was mainly due to the high thermal expansion coefficient of this metal. This resulted in residual compressive stresses in the coating, whereas the low thermal expansion coefficients of Ti and Ti6A14V produced residual tensile stresses. The tensile stress in the coating over Ti and Ti6A14V substrates caused the coatings to buckle and crack, thereby greatly decreasing their bonding strengths.