The Naval Surface Warfare Center Carderock Division (NSWCCD) has developed, prototyped, and patented a cost-effective method of creating aluminum engine cylinders with better physical characteristics, longer life, and improved performance. The centrifugal casting technique incorporates silicon monoxide (SiO) into molten aluminum alloy to create a harder inner surface.
Silicon monoxide is considerably harder than aluminum and the aluminum alloys typically used in engine cylinders. It also has a lower specific gravity than liquid aluminum, melts at a much higher temperature than aluminum, and does not dissolve in or react with aluminum. Because of these properties, SiO remains solid and moves to the inner surface when injected into molten aluminum in a centrifugal casting system. The result is a 1-5mm zone where the SiO is concentrated with aluminum/aluminum alloy. The presence of the SiO increases wear resistance, but the mixing with aluminum helps overcome strength losses inherent in other techniques that insert harder materials into aluminum.
- High Strength: Silicon monoxide has a hardness similar to silicon (7 on the Moh’s scale) compared to a 2.5-3 Moh’s hardness measurement for aluminum
- Economical: Centrifugal casting is an inexpensive technique and silicon monoxide is a commercially available material
- Hardness and Strength: Silicon monoxide provides wear-improving hardness, but losses in strength are largely mitigated by surrounding each silicon monoxide particle with an equal diameter of aluminum or aluminum alloy
- US Patent 8,141,615 is available for license and commercialization
- Potential for collaboration with NSWC Carderock Division inventor