A study on porous super austenitic stainless steel coating for improvement of bone ingrowth

Abstract

In this study, the prostheses were provided with the bone ingrowth site by coating the super stainless steel powder on the same substrate ($32050) using plasma spraying method. Plasma current and powder feed rate varied in this study based on the optimum conditions of previous experiments. The optimum conditions for satisfying the requirements of the porous coatings were found. The characteristics of the coatings were observed according to the experimental parameters. It was found that plasma current influenced the chemical composition (the oxides, Cr component), melting and flattening degree of the sprayed particle (surface roughness, thickness of the splat, pores) and corrosion -resistance. The powder feed rate also influenced the coating thickness and efficiency. The amount of Cr was increased, but Ni, Mo, Fe were decreased with plasma current. An increase of Cr in the coating surface corresponded to an increase in the amount of the formed oxides. The coated specimen in 400A had a high corrosion-resistance owing to a dense coating. The coated specimen in 500A formed many types of oxides. In 300A current, the coating was rough with many pores, and corrosion-resistance of the coating showed a large variation according to the oxidation and compositional change. Specifically at 100 g/min powder feed rate in a 300A current, the coating was rough and porous, nevertheless, it had high corrosion resistance.

Properties of super stainless steels for orthodontic applications

“…Much effort has gone into satisfying these needs and into improving the properties of stainless steels. Super stainless steels that have higher corrosion resistances and greater mechanical strengths than the conventionally used stainless steels have been developed,3–5 and these could overcome disadvantages such as high cost, low shear strength, low wear resistance, low formability, and low weldability of titanium alloys 6–8. Super austenitic stainless steel (SR‐50A) was reported to have localized corrosion resistance which is similar to those of titanium alloys, because the passive film is enhanced by the synergistic effects of high nitrogen and molybdenum content 5–11.…”

“…It was believed that this passive film minimized the amount of metal dissolved in the mouth. The super stainless steels used in this study are super austenitic stainless steel (SR‐50A),6–8, 11 super martensitic stainless steel (SR‐3Mo),12 super duplex stainless steel (SR‐6DX),13 and super ferritic stainless steel (SFSS) 14. These steels were developed for the enhancement of passive film by synergistic effects of Mo‐N or high addition effect of Cr‐W 6–14…”

“…To date, relatively few studies have been made on the mechanical properties and corrosion resistance of super austenitic stainless steel and on their applicability to the orthodontic field 20. Oh and co‐workers7, 8, 20 reported upon the biocompatibility of super austenitic stainless steel and upon hydroxyapatite and porous‐metal‐coated super stainless steels. Comparison of the results of corrosion testing for the HA and porous steel coating on the super stainless steels and 316L SS in Hank's solution and 3.5% NaCl solution shows that the super stainless steel had higher crevice and pitting corrosion resistance than the 316L SS 7, 8.…”

“…Oh and co‐workers7, 8, 20 reported upon the biocompatibility of super austenitic stainless steel and upon hydroxyapatite and porous‐metal‐coated super stainless steels. Comparison of the results of corrosion testing for the HA and porous steel coating on the super stainless steels and 316L SS in Hank's solution and 3.5% NaCl solution shows that the super stainless steel had higher crevice and pitting corrosion resistance than the 316L SS 7, 8. The properties of super stainless steel wire in orthodontic application have also been studied 20.…”