New custom metal and alloy treatment processes have been created by SANOVA for development of advanced, ultra-high-temperature aerospace materials, which would provide high performance and/or high cost payoffs in such applications as solid rocket nozzle propulsion components, for example.
In one recent project SANOVA proposed to manufacture the entire component required to operate in the high-temperature environment (rocket nozzle in this case) from applicable refractory material, such as Ta, and then treat the outer surface of the nozzle shell with SANOVA's custom technology to generate precise, highly durable protective diffusion case. While the nozzle's core will possess high strength and other desirable mechanical properties of Ta, the protective TaC and TaN diffusion case on its surface, generated by SANOVA process, shall be highly resistant to wear, oxidation, corrosion and erosion at high temperatures. Treatment technology prototype LINTERTANTALUM-C1 was created by SANOVA in that project.
Processing parameters of our treatment technology created for this application were set to achieve depth and properties of the diffusion protective surface layer necessary to meet, and possibly exceed current time and service requirements of the nozzles. Tantalum was used in our work as an example, as we believe it to be a strong material candidate for nozzle manufacturing, but other refractory metals can be considered for their specific properties.
Achieved results, presented below, clearly demonstrated that diffusion case depth of protective surface layers generated with CARBOTANTALUM-1 technology on the surface of Ta substrate, as for any other refractory metal, can be precisely controlled with simple variation of treatment process parameters. Case depth of 700 µm (0.7 mm) was achieved after 10 min of LINTERTANTALUM-C1 processing and the depth of 1200 µm (1.2 mm) after 30 min. of processing. Outer-most layer contains maximum concentration of carbon and consists of super-hard TaC (with hardness values exceeding 1700 Hk!) with extremely high melting temperature of 3980° C (7196° F) and superior high-heat, wear, erosion, oxidation and corrosion resistance.
Microstructure of diffusion (a, b) surface layer of commercially pure Ta (Ta?021) after LINTERTANTALUM?C1™ processing on laboratory equipment LINTERLAB?I2.
Microstructure (X25, x 100, x500) of the top surface of the standard small test specimen # Ta?021 after corresponding LINTERTANTALUM?CI™ processing.