SBIR-STTR Award

The purpose of this research program is to exploit some newly discovered alloy phases based on alloy-modified cubic al3ti as coating materials for high temperature titanium based alloys. The new alloys formed by adding chromium or manganese to al3ti readily form a desirable scale of al2o3 in oxidizing atmospheres and have greatly improved mechanical properties and oxidation resistance (at 2200 deg f) over earlier modifications of al3ti. The program will use state-of-the-art low pressure plasma spray techniques to produce coatings on both conventional and intermetallic titanium based alloys. Powders of the coating alloys to be used in the plasma spray process will be produced by a state-of-the-art atomization process.

A preliminary study funded by a Phase I SBIR contract has demonstrated that adherent coatings of chromium-modified, cubic phase Al3Ti can be applied to Ti-base materials using the vacuum plasma spray (VPS) process. The coatings provided protection during cyclic oxidation testing between 700 degrees C and room temperature for more than 200 one hour cycles. Also, high quality, prealloyed Cr-modified Al3Ti powders were manufactured using the High Pressure Gas Atomization process. However, additional work must be performed to develop these coatings into a predictable and economical Ti-base materials protection system. The Phase II research program will be conducted in two stages. The first will consist of a series of goal-oriented, VPS coating experiments designed to address specific problems identified by the Phase I work. The second stage will consist of a small scale production run of VPS coated mechanical test bars. This will allow the substrate/coating combination to be subjected to tensile fatigue, bending and oxidation tests for further evaluation and to obtain engineering data. The statistical variation of the results will be analyzed and used to identify aspects of process control that will be in need of attention during Phase III production.

Keywords:
COATINGS OXIDATION RESISTANCE TITANIUM ALUMINIDES VACUUM PLASMA SPRAY TITANIUM ALLOYS