High Performance Valve Seat Materials for CNG Powered Combustion Engines.

Area of Science:

• Materials Science
• Mechanical Engineering
• Automotive Engineering

Background:

• Conventional copper infiltrated high speed steel (HSS) valve seats fail in gasoline engines using compressed natural gas (CNG) due to higher exhaust gas temperatures (80°C+).
• This leads to drastically shortened service life of engine valves in CNG-fueled engines.

Purpose of the Study:

• To design and evaluate a novel high-alloy HSS-base material for valve seats resistant to hot corrosion and mechanical wear in CNG engines.
• To assess the performance and durability of these new valve seats under simulated operating conditions.

Main Methods:

• A proprietary high-alloy HSS powder was processed, including vacuum annealing to reduce oxygen and improve compressibility.
• Manganese sulfide (MnS) was added to enhance machinability, followed by compaction and sintering at 1135°C in nitrogen.
• The sintered components were infiltrated with a copper alloy and subjected to a 100-hour automotive industry valve seat wear test.

Main Results:

• The developed HSS valve seats exhibited very slow wear rates during the 100-hour engine test.
• Both periodic and final examinations confirmed the material's resistance to wear under CNG combustion conditions.

Conclusions:

• The novel high-alloy HSS valve seats are highly suitable for use in compressed natural gas (CNG) powered engines.
• The material design effectively addresses the challenges of hot corrosion and mechanical wear, extending engine valve service life.