Sputtered austenitic manganese steel

Manganese steel of the typical Hadfield composition (1%C, 13%Mn) is well known for its remarkable properties of abrasion and wear resistance under loads of sufficient severity to cause work hardening. Hadfield steel coatings about 75 to 100 μm thick were deposited on tantalum and metallurgically polished copper substrates using a hollow cathode sputtering apparatus. Substrate temperatures ranged from 1000°C to those provided by liquid nitrogen cooling. X-ray diffraction measurements indicated that the occurrence of austenite (γ) and ferrite (α) phases in the as-deposited coatings was consistent with the equilibrium phase diagram: γ phase at 1000°C, γ + α from 600 to 400°C and α below 400°C. Metallographic cross sections revealed (1) that the structure varied from fibrous to columnar with increasing substrate temperature and (2) that the γ and the γ + α deposits included a dispersed iron carbide phase. Coatings deposited at temperatures above 400°C exhibited a moderate hardness (KHN ≈ 350 kg mm^?2). However, those deposited at lower temperatures (< 300°C) exhibited a distorted b.c.c. (martensite-like) structure and yielded hardnesses equivalent to the highest values reported for work-hardened Mn steel (KHN = 750 kgmm^?2).     

Search methods used with transistor patent applications

As the world has become more technically oriented, the number of patent applications has been increasing also?too rapidly for the Patent Office to assimilate them comfortably with current techniques. When an application for a patent is received, it must be evaluated as to novelty by a specialist who searches the prior art for similar patents. Previously, all such searches were done manually, which meant that the examiner had to rely entirely on his knowledge and experience. In an effort to remedy the situation the Office has instituted mechanized search methods. In order to ascertain the differences in patterns of thinking associated with manual and mechanized searches, a study was carried out in which a patent application in the transistor art was searched both manually and by a mechanized method. The mechanized search in this case permitted more patents to be analyzed more quickly but, being completely literal, it does not allow for hunches or browsing.