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Pore-free aluminium castings
Urethane R R I M cuts costs on M G Metro Turbo When the Metro Turbo was developed, it became clear that the wider wheels and tyres necessary to match the car's higher performance would need wider wheel arches to achieve proper clearance. Since it would have been uneconomic to re-tool the Metro's wing panels for this smaller volume application of 7000 units per year, it was decided instead to extend the wheel arches by adding 'eyebrow' mouldings of glass-filled RRIM polyurethane. The styling thus established was continued into the Turbo's lower front spoiler, also moulded in RRIM and complete with air inlets for front disc brake cooling. The rear spoiler, which surrounds three sides of the rear window, to give an aesthetically pleasing effect, was first developed for the (non-Turbo) M G Metro, whose planned production rate is 20,000 units per year. The spoiler is a glass-reinforced RIM moulding, which is simply added to the standard Austin-Metro body shell. No changes in metal tooling are therefore involved.
Pore-Free Aluminium Castings In a newly developed proprietary process aluminium wheels and other products were die-cast free of pores. Normally, entrapment of air in a casting is a disadvantage of conventional die-casting techniques. The presence of porosity limits the containment of pressure and contributes to variations in uniform strength as well as hindering heat treatment and welding.
Silicon Carbide Coating For Embrittlement Protection At High Temperatures Refractory glass cloth gap filler, which is used to seal the gaps between the Space Shuttle orbiter insulating tiles, has been coated with a suspension of silicon carbide and polyethylene in butanol to increase its useful life. The emittanee of the cloth coated with silicon carbide is increased from 0.3 - 0.4 to 0.7 - 0.8. As a result a lower temperature is maintained. Uncoated cloth filler normally operates at 1,260°C; However,
MATERIALS & DESIGN, Vol. 4 APRI~_/MAY 1983
The components are moulded in self-coloured black, which is well suited to the MG's two-tone sporting style. A welcome extra advantage of using polyurethane for the wheel arch extensions is that they resist the occasional scrapes which may be suffered by these, the widest parts of the body. All the components are moulded for Austin Rover by Holden Hydroman.
Cast Forge Company, a unit of Kelsey-Hayes Company, has developed a new technique in which the die cavity is prefilled with oxygen. The injection of molten metal into the cavity results in chemical combination of the aluminium with oxygen, forming a fine dispersion of solid oxide. The net result is the formulation of a highly reliable casting suitable for heat treatment and welding. The new process is reported to combine the best features of low-pressure permanentmould casting and high pressure casting. The pore-free casting is independent of casting pressure, providing high quality with low scrap and comparable production rates. The method produces equivalent tensile strength values which are independefit of casting size. S. Lee
when coated with silicon carbide, the temperature is lowered to 1,030°C. The work performed at the Johnson Space Center by Calvin Schomburg and Robert L. Dotts has shown that the glass cloth becomes embrittled when exposed to the extreme temperatures encountered on re-entry into the earth's atmosphere and only 25% of the thousands of fillers are reusable after each mission. However, using the silicon carbide coating, 85% of the coated glass cloth is reusable. The method of application is either spraying or brushing the silicon carbide/polyethylene/butanol suspension. The purpose of the polyethylene is to ensure that the suspension contains a low viscosity which is sufficient to penetrate the cloth fibers. The butanol vehicle evaporates and the polyethylene is pyrolyzed when the temperature reaches 538°C. Other combinations of emittance-control and suspension agents were investigated, but were not as successful regarding to temperature resistance and flexibility as the silicon carbide/polyethylene/butanol suspension. S.M. Lee
697
Pore-Free Aluminium Castings In a newly developed proprietary process aluminium wheels and other products were die-cast free of pores. Normally, entrapment of air in a casting is a disadvantage of conventional die-casting techniques. The presence of porosity limits the containment of pressure and contributes to variations in uniform strength as well as hindering heat treatment and welding.
Silicon Carbide Coating For Embrittlement Protection At High Temperatures Refractory glass cloth gap filler, which is used to seal the gaps between the Space Shuttle orbiter insulating tiles, has been coated with a suspension of silicon carbide and polyethylene in butanol to increase its useful life. The emittanee of the cloth coated with silicon carbide is increased from 0.3 - 0.4 to 0.7 - 0.8. As a result a lower temperature is maintained. Uncoated cloth filler normally operates at 1,260°C; However,
MATERIALS & DESIGN, Vol. 4 APRI~_/MAY 1983
The components are moulded in self-coloured black, which is well suited to the MG's two-tone sporting style. A welcome extra advantage of using polyurethane for the wheel arch extensions is that they resist the occasional scrapes which may be suffered by these, the widest parts of the body. All the components are moulded for Austin Rover by Holden Hydroman.
Cast Forge Company, a unit of Kelsey-Hayes Company, has developed a new technique in which the die cavity is prefilled with oxygen. The injection of molten metal into the cavity results in chemical combination of the aluminium with oxygen, forming a fine dispersion of solid oxide. The net result is the formulation of a highly reliable casting suitable for heat treatment and welding. The new process is reported to combine the best features of low-pressure permanentmould casting and high pressure casting. The pore-free casting is independent of casting pressure, providing high quality with low scrap and comparable production rates. The method produces equivalent tensile strength values which are independefit of casting size. S. Lee
when coated with silicon carbide, the temperature is lowered to 1,030°C. The work performed at the Johnson Space Center by Calvin Schomburg and Robert L. Dotts has shown that the glass cloth becomes embrittled when exposed to the extreme temperatures encountered on re-entry into the earth's atmosphere and only 25% of the thousands of fillers are reusable after each mission. However, using the silicon carbide coating, 85% of the coated glass cloth is reusable. The method of application is either spraying or brushing the silicon carbide/polyethylene/butanol suspension. The purpose of the polyethylene is to ensure that the suspension contains a low viscosity which is sufficient to penetrate the cloth fibers. The butanol vehicle evaporates and the polyethylene is pyrolyzed when the temperature reaches 538°C. Other combinations of emittance-control and suspension agents were investigated, but were not as successful regarding to temperature resistance and flexibility as the silicon carbide/polyethylene/butanol suspension. S.M. Lee
697