OPTIX for Hot Isostatic Pressing (HIPING)

?Hot Isostatic Pressing (HIPING) is a process to densify powders or cast and sintered parts in a furnace at high pressure (100-200 MPa) and at temperatures from 900 to 1250°C eg., for steels and superalloys.

 HIPING has developed to become a high-performance, high-quality and cost-effective process to produce many metal (or ceramic) components.

HIPING is currently employed for the manufacture of parts used in many industry sectors. Some examples of these include:

? Energy

? Process Industry and Tooling

? Transportation and Aerospace

? Nuclear and Scientific

? Oil and Gas

HIPING uses canisters to contain the metal/ceramic powders and must be leak tested, by evacuating the container. Once assured that the container is leak-free, the powder is introduced. The next step is outgassing to remove adsorbed gases and water vapor, the degassing process is achieved by vacuum pumping with the end-point for the process being poorly defined. Degassing is a critical, time-consuming step in the manufacture of powder hot isostatic pressed components. Effective degassing of HIP canisters is paramount to producing high quality components by prevention of the retention of atmospheric contaminants such as oxygen, nitrogen, hydrogen and argon. These contaminants are responsible for defects that lead to poor materials performance and reducing confidence in HIP products. The solution to degassing of large HIP canisters ready for processing is often met with extended degassing times to ensure adequate. Outgassing of canisters can take up to several days to complete.

The Optix gas sensor is a device that can be utilised to monitor the level of gases such as water vapour, nitrogen, oxygen etc. OPTIX can operate during the initial pump-down phase and during the outgassing. Unlike other vacuum gas analysis methods, OPTIX is a highly sensitive stand-alone device that is industrially hardened to ensure 100% operation uptime even in the harshest environments.

Therefore, considerable time saving can be achieved by monitoring the degassing process with the Optix sensor to detect and notify users when degas is complete based on the residual gas analysis to shorten processing times for Hiped parts, whilst ensuring quality.

Optix can also be used for monitoring the HIP argon gas and its impurities is required to control the quality and repeatability of the process. This requires the analysis of the trace impurities in a range of 0-100ppm for H2-O2-N2-CH4-CO-CO2-NMHC-H2O in UHP argon.

Optix benefits:

Wide range pressure measurement

Leak checking of Hiping enclosures

Monitoring the effectiveness of the pump-down

Monitor degassing and gas partial pressures to determine the correct pump down time

Sampling of gas during HIPING to check purity of argon

Traceability for parts – data saved of residual gas traces during all process stages

Ref: Morrison, Taylor, Burtt & Carpenter doi.org/10.1080/00325899.2020.1843257