Glossary

What are transonic airfoils, and what is the active clearance control? Check out our technical dictionary and find out more about engine technology terms – from active clearance control to velocity triangle.

Cadmium-plating Can-annular combustion chamber Can-type combustion chamber Cascade axis Cascade front Cascade normal Cascade spacing Case-hardening CBN hardfacing of blade tips Ceramic Coating Ceramics CFRP structures Chemical conversion Chromate treatment of aluminum

Chromate treatment of magnesium Chromic acid anodizing CLEAN Cleaning Columnar crystal Combustion chamber Component efficiency Compressor Control system Cooling air holes Copper-plating Crack inspection Critical Mach No.

CBN hardfacing of blade tips

During engine operation temporarily increased centrifugal forces may cause the blade tips to contact the casing. In the high-pressure compressor the heat of friction may cause an exothermal reaction owing to the blade material used (titanium alloys) and, under certain conditions, even an engine fire.

To prevent this, the tips of the high-pressure compressor blades are hardfaced by brazing on CBN grains. In blisk production induction brazing in vacuum is used for the purpose. When the engine is running and contact occurs between blade tips and casing the CBN grains erode the casing inner wall. Direct contact between the base material of the blades and that of the casing is thus no longer possible.