In line with its self-reliance mission, ISRO has developed an alternative for the imported Columbium material used for the nozzle divergent in the fourth stage of the PSLV launch vehicle. It has indigenously developed the nozzle divergent made of Stellite. This alternate material is a cobalt-based alloy with additions of Chromium, Nickel, Tungsten and Iron.

The tests conducted on the Stellite made nozzle divergent has proved that it can retain strength at high temperatures up to 1150 degree Celsius. ISRO had conducted three tests earlier and a final test on April 8th where it was proven successful after a hot test lasting for a duration of 665 seconds.

The test was conducted at the ISRO Propulsion Complex in Mahendragiri in Tamil Nadu. The use of Stellite nozzle divergent in PSLV will save ISRO 90 percent of the cost incurred on imported Columbium. The ISRO facility in Mahendragiri had also successfully carried out hot tests of the human-rated Vikas Engine to be used for the Gaganyaan programme. Vikas engine is designed and developed within the country and is named after Vikram Sarabhai, the father of the Indian Space programme. The human-rated launch vehicle LVM 3 G will use two Vikas engines in a clustered configuration to carry the astronauts to outer space.