Papers by Keyword: Vacuum Plasma Spraying

Abstract: Plasma sprayed hydroxyapatite (HA) coatings on titanium alloy substrates have been used extensively due to their excellent biocompatibility and osteoconductivity. However, the low bonding strength between HA and Ti substrates is still problematic in the long-term implantation lifespan. In this paper, HA/Ta composite coatings with various Ta contents (20% and 60%) were fabricated by vacuum plasma spraying (VPS). The microstructure, phase composition of the coatings was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The results revealed that the coatings had a rough surface and lamellar structure including some pores. ASTM C-633 standard was used for the measurement of bonding strength, which was found increasing with the increase of Ta contents in the composite coatings. The bonding strength of the composite coating containing 60% Ta (H4T6) reached to 37.2 MPa, which is about 1.9 times that of HA coating. In vitro bioactivity evaluated in simulated body fluids (SBF) showed that bonelike apatite layer was formed on the composite coatings surface, which indicated the good bioactivity of the HA/Ta composite coatings.

Abstract: Biomaterials with good biocompatibility and anti-bacterial property were becoming attractive to researchers, so we used the chemical method to produce anti-bacterial vacuum plasma sprayed titanium coatings and studied In vitro bioactivity, cytotoxicity and blood compatibility of the anti-bacterial coatings in this paper. In order to evaluate the bioactivity of the treated titanium coatings, the coatings were immersed in simulated body fluid (SBF). The treated titanium coatings showed good bioactivity in this experiment. Two different methods were used to assess the cytocompatibility of the treated titanium coatings. One was extract test; the other was direct contact test. The results indicated that cells spread and adhered well on the coatings. The blood compatibility of the coatings was evaluated by haemolysis ratios. The hemolysis ratios of the coatings were below 2%, indicating of nonhemolysis for the coatings.

Abstract: In this paper, antibacterial silver-containing hydroxyapatite coating was prepared by vacuum plasma spraying method and osteoblasts were seeded onto the surface of the coating to evaluate its cytocompatibility. The results indicated that the cells proliferated well on the samples, and the proliferation rate on the silver-containing hydroxyapatite coating was a little bit higher than that on the silver-free hydroxyapatite coating. The contact angle of water drop on the coating was measured, and it was found that the contact angles of the silver-containing hydroxyapatite coatings were smaller than the hydroxyapatite coating. The improvement of hydrophilicity for the silver-containing hydroxyapatite coating could be beneficial to the cells proliferation on its surface. It can be concluded that the addition of silver in the hydroxyapatite coating endowed the coating with antibacterial property while maintaining its excellent cytocompatibility.

Abstract: Vacuum plasma sprayed (VPS) hydroxyapatite (HA) coatings with silver-loaded zirconium phosphate antimicrobial have been prepared on titanium substrate. Antibacterial effects of the coatings were studied by bacteria culturing using Porphyromonas gingivalis (Pg), Fusobacterium nucleatum (Fn) and Actinobacillus actinomycetemcomitans (Aa) as microorganisms. Simulated body fluid (SBF) test was carried out to evaluate the bioactivity of the coatings as well. The results obtained showed that the coatings exhibited a marked antibacterial effect against Pg, Fn and Aa when the content of antimicrobial was equal to or more than 5%. The antibacterial capability of the coatings decreased in the following order: Pg, Fn, Aa. Bone-like apatite layer was formed on the silver-containing HA coatings after immersed in SBF, suggesting that their bioactivities were not affected obviously by the addition of silver-zirconium phosphate antimicrobial. This study indicated that silver-containing VPS HA coating is a prospective candidate as dental material.

Abstract: Metallic amorphous materials have been widely developed thanks to the outstanding properties including high chemical stability, mechanical strength, and magnetic properties. However, with the exception of a few compositions, the limiting factor is the critical cooling rate for the formation of the amorphous phase. For many applications, it is only the contact surface properties that are important, thus the use of coating techniques such as thermal sprayings has several attractive features. In this paper, we present the microstructure of Ni-based amorphous coatings prepared by laser cladding and vacuum plasma spraying. The utilization of plasma spraying to deposit atomized powder enabled the formation of fully amorphous coating, laser cladding resulted in mostly crystallized structures. Glass forming ability and wear properties of the coatings were discussed as a function of the coating microstructure.