Method for preparing ceramic coat with biphase gradients of zirconia and alumina on surface of zirconium base

Abstract

This invention discloses a process for preparing zirconium oxide-aluminum oxide biphase gradient ceramic coating on the surface of zirconium-based material. The process comprises: preparing an electrolyte, supplying zirconium or zirconium alloy as the anode and metal stainless steel as the cathode (spacing = 8-12 cm), and performing micro-arc oxidation treatment on zirconium or zirconium alloy at an electrolyte temperature of 15-40 deg.C, a constant voltage (supplied from an impulse power supply) of 300-650 V, an initial current density of 6-20 A / mm2, a frequency of 50-1000 Hz, and a duty ratio of 5-40% for 25-90 min to obtain the product. The zirconium oxide-aluminum oxide biphase gradient ceramic coating is composed of t-ZrO2 and alpha-Al2O3 biphase, and the content of alpha-Al2O3 biphase is decreased from the surface to the matrix. The zirconium oxide-aluminum oxide biphase gradient ceramic coating has a nanoporous structure and no interface with the matrix, and thus has high combination strength and high hardness (above 1200 Hv).

Description

technical field [0001] The invention relates to the composition and preparation method of a zirconia-alumina dual-phase gradient coating on the surface of a zirconium base, in particular to a zirconia-alumina dual-phase gradient coating material used on the surface of zirconium and zirconium alloy components and its Micro-arc oxidation preparation process. Background technique [0002] The hip and knee joints are the main load-bearing and wear parts of the human body, and have the highest damage rate among all kinds of joints. Replacement prosthesis used to restore its function - artificial hip and knee joints are composed of joint head, joint socket and joint stem. Among them, the joint head and the joint socket are mainly subject to wear, so it is required that the constituent materials have strong wear resistance, low wear particle generation rate, sufficient strength and toughness, and good biocompatibility to ensure a long service life. [0003] Artificial hip and kne...

AI Technical Summary

Problems solved by technology

Although metals represented by cobalt-chromium-molybdenum alloys, stainless steel and titanium alloys have good strength and toughness, they have low hardness and poor wear resistance.

Alumina (Al 2 o 3 ) has high hardness (about 20GPa) and low friction coefficient, but its strength is low, toughness is poor, and it is prone to fragmentation

Tetragonal zirconia (t-ZrO 2 ) is more than twice as strong and tough as alumina, and its hardness is about 12GPa. It was once considered the best material for hip joints. However, its aging degradation in the body fluid environment makes its long-term service safety subject to many Scholars question

All of these, the existing technology is still unable to obtain a zirconia-alumina dual-phase gradient coating that has both large thickness and strong bonding performance, and keeps the substrate zirconium alloy at low temperature without deteriorating its own mechanical properties.