| 摘要 |
<p>Metal casting cores and moulds are made from sand bonded with a silicate (pref. Na, K, Et) and hardened by the passage of CO2. The sand is first coated with a scouring agent (pref. light pptd magnesite or 85-90% fluorspar), and supplied in a moist condition in sealed containers to the smelter. Opt. a refractory (pref. olivine) is included. Better quality products are obtained and the raw material can be stored for several months without drying.</p> |
