GB767532A - Improvements relating to the manufacture of plates from powdered substances - Google Patents

Abstract

767,532. Moulding powdered potassium bromide &c. PARSONS & CO., Ltd., C. A. April 22, 1955 [June 10, 1954], No. 17114/54. Class 87(2). For making transparent plastic from powders such as potassium bromide and other alkali halides, for use in spectrometers, by compression between highly polished steel plates in a die from which air is evacuated, the high pressure required is exerted by a constrained metal bar when heated. The polished steel plates or anvils 7, 8 fit in a cylinder 6 in a casing 5, the anvil 8 and a plunger 4 being free to slide in the cylinder and inserted after the powder 9 has been placed on the anvil 7. Air is evacuated through a duct 10 connected to a suction pump. A steel bar 3 is gripped between the top of the plunger 4 and a screw 2 which exerts moderate pressure on it, and it is heated by a gas flame to a temperature sufficient to cause it to expand and produce the additional pressure required to compress the powder into a plate. To show when the heating may be stopped the strain in the frame may be indicated. A rigid L-shaped member 12 may be fixed to the frame 1 at 18, and a block at 13, enabling the strain to be observed by measuring, with a micrometer, the distance between parallel surfaces 19, 20. Such an arrangement may be modified to incorporate a pair of electrical contacts which break at a desired plunger load and open the circuit of an indicating lamp. Alternatively the temperature may be observed, e.g. by the use of temperature sensitive paint.