Progress in Titanium Precision Casting
Florian Bulling, from the Research Institute for Precious Metals and Metals Chemistry, unveils the latest promising results for creating higher-performance titanium alloys
Titanium alloys are known for their good mechanical properties, high corrosion resistance and low density. The Ti- 6Al-4V alloy, also known as grade 5 titanium, is the most commonly used. Other titanium-based alloys are the intermetallic NiTi compounds (Nitinol®). Due to their super elasticity, they are used as materials for stents or actuators. Induction melting and investment casting have been compromised by crucible reactions. The conventional crucible materials, such as alumina or quartz are not suitable, due to the ceramic decomposition by coming into contact with titanium in the liquid state. Even highly stable refractories, such as zirconia or yttria, which are used as crucible linings, are not sufficiently stable. For this reason, a new ceramic material based on calcium zirconate seems to be the solution. This is a synthetic ceramic material that is produced by melting a stoichiometric mixture of calcia and zirconia in an arc furnace. It has recently been introduced and is showing very promising properties as a material for crucibles and shells. This material has been successfully tested for grade 5 titanium alloy by precision casting.
