Notes on dental metallurgy : for the use of dental students and practitioners / by W. Bruce Hepburn.

  • Hepburn, W. Bruce (Walter Bruce)
Date:
1911
Catalogue details

Licence: In copyright

Credit: Notes on dental metallurgy : for the use of dental students and practitioners / by W. Bruce Hepburn. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

    45/234 (page 33)
    CASE-HARDENING OF STEEL.—Articles to be hardened are packed in air-tight cases surrounded by such animal carbon producers as leather, bone dust, hoofs or horns, etc., with a little soda or lime. The box and contents are gradually heated to redness, and maintained at this heat for a time depending on depth of case-hardening required. Superficial hardening is obtained by dipping red-hot iron into prussiate of potash, and then plunging into cold water. Case-hardening is employed where friction is to be resisted, for lathe-heads, engine bearings, etc., and imparts to the metal an extremely hard skin, which resists metal files. The process is also employed for hardening armour-plates. HARVEYIZING OF STEEL.—This is a modifi- cation of the cementation process, whereby the outer thickness of a mild steel plate is caused to take up an additional percentage of carbon, and so acquires increased power to resist penetration. The steel to be Harveyized is laid in chests on a furnace bed of fire-bricks and sand ; carbon is tightly packed around it, and the chests are covered with fire-bricks. The temperature is raised to about 1,200° C, and retained at this heat until the steel has absorbed i per cent, of carbon ; and the carbon having penetrated as far as is required, the furnace is allowed to cool slowly. The steel produced is extremely hard on the surface, while it still possesses the properties of mild steel throughout the rest of its depth. 1 3