Clock mechanism parts prodn - from glass turned semicrystalline

摘要

Very small objects, in particular part of clock or watch mechanism are produced from glass contg. as lattice-forming elements oxides of Si, B, Ge, P or As, and as intermediate modifiers oxide of Al, Be, Mg, Li, Ca, Na, Ba, K, Zn, Mn, Pb, Cd, Sr, Ni, Fe(II) and Co with addition of an agent promoting devitrification of the glass (pref. a colloidal dispersion of Ru, Re, Pd, As, In, and/or Pt). The parts are formed by casting and moulding molten glass, and slowly cooling to solidification; the temps is kept for some time at a temp. corresp. to a viscosity of 102-1013 P to stabilise the product and start the devitrification process. Subsequently the parts are subjected to thermal treatment promoting crystallisation and yielding a fine-grained opaque ceramic material free of pores.