THIN LAYERS MEANT TO IMPROVE CERAMIC-TO-METAL ADHERENCE IN PROSTHETIC DENTAL RESTORATION

摘要

The invention relates to materials made of thin layers as hard multilayers adhering to metal substrates of NiCr and CoCr on which they are deposited, exhibiting corrosion resistance and biocompatibility properties, meant to be used to improve adhesion between metal and ceramics within fixed prosthetic restorations of the metalo-ceramic type obtained by a method of physical deposition in vapour state. According to the invention, the material is made of successive layers, the first layer being a MeN nitride layer, where Me is one of the metals in the series Ti, Zr, Cr and Ta, the second layer being a MeSiN silicon-nitride layer and the third layer being a silicon-oxy-nitride layer, having the total thickness in the range of 1.3...3.3 μm, exhibiting high adherence to the substrate, normal critical forces upon the scratch adhesion test in the range of 48...68 N, a hardness in the range of 26...38 GPa, the ion amount released in Fusayama artificial saliva being 25 μ g/cm, the corrosion rate 4x10mm/year and a cell viability factor 85% upon the cytotoxicity test, the metal substrate-multilayer-ceramics system exhibiting stresses of breaking up/crack initiation upon the three point bending tests in the range of 30...50 MPa which are superior to those of the systems without adhesion layer that range between 26...28 MPa.