Papers by Author: Ri Zhi Wang

Abstract: Nacre powder suspensions in alcohol added with acetic acid (Suspension I) or calcium chloride (Suspension II) were prepared. Titanium substrates were coated with nacre powder by EPD in the suspensions. The result shows that Suspension II is more stable than Suspension I, and deposition rate in Suspension II is much higher than that in Suspension I. XRD and FTIR results show that the nacre coatings exhibit the same characteristics as the raw nacre powder. SEM morphologies show that uniform coatings are achieved. Scratch test shows that bonding strength of coatings from Suspension I is much higher than that of Suspension II. The higher bonding strength from Suspension I was confirmed to be closely related to the concurrent deposition of organic molecules dissolved in the suspension.

Abstract: Titanium dental implant screws were implanted into the pearl sacs of a fresh water bivalve (hyriopsis cumingii Lea) by replacing the pearls. After 45 days of cultivation, the implant surfaces were deposited with a nacre coating with iridescent luster. The coating was about 200-600 µm in thickness and composed of a laminated nacreous layer and a transitional non-laminated layer that consisted mainly of vaterite and calcite polymorphs of calcium carbonate. The transitional layer was around 2-10 µm thick in the convex and flat region of the implant surface and could form close contact with titanium surface; while the transitional layer was much thicker in the steep concave regions and could not form close contact with the titanium surface. The improvement to the design of the dental implant with respect to this coating method was suggested in the paper. The results suggest that it is possible to fabricate a biologically active and degradable, and mechanically tough and strong nacre coating on titanium dental implant by this novel coating technology.