Abstract: A method of case hardening an article formed of titanium, zirconium or an alloy of titanium and/or zirconium is disclosed. First, the article is heat-treated in an oxidizing atmosphere at a temperature in the range of 700 to 1000° C. so as to form an oxide layer on the article. Then, the article is further heat-treated in a vacuum or in a neutral or inert atmosphere at a temperature in the range of 700 to 1000° C. so as to cause oxygen from the oxide layer to diffuse into the article.

Abstract: The tribological behavior of titanium or titanium alloy article is improved by gaseous oxidation of the article at a temperature in the range of 500 to 725° C. for 0.5 to 100 hours, the temperature and time being selected such as to produce an adherent surface compound layer containing at least 50% by weight of oxides of titanium having a rutile structure and a thickness of 0.2 to 2 &mgr;m on a solid solution-strengthened diffusion zone wherein the diffusing element is oxygen and the diffusion zone has a depth of 5 to 50 &mgr;m.

Abstract: A titanium alloy product having good tribological properties without the need to introduce an alloying element into the surface is produced by casting or casting and forging a titanium alloy consisting of 2 to 15% by weight silicon or 5 to 15% by weight nickel, 0 to 7% by weight of at least one strengthening element selected from aluminum, tin, zirconium, chromium, manganese, iron, molybdenum and niobium, and 0 to 2% by weight of a surface improving alloying element selected from boron, carbon, nitrogen, oxygen, and zirconium, the balance apart from impurities and incidental ingredients being titanium. Such alloy is then surface treated by surface melting and rapid solidification so as to produce a hard, wear-resistant surface layer without substantially affecting the bulk properties of the alloy.

Abstract: A method and apparatus for separating magnetically susceptible particles from a mixture of magnetically susceptible particles and non-magnetic or less magnetically susceptible particles in which a stream containing the mixture in a fluidized condition is introduced under pressure or under gravity into one end of an arcuate separation channel having an inlet end and an outlet end and arcuate inner and outer walls and at least one connecting wall which confine the steam and constrain it to flow in a single unidirectional arcuate path along the channel in frictional contact with the inner and outer walls and with the connecting wall, the velocity of the stream and the frictional resistance to flow being such that the stream is subject to sufficient centrifugal force as it flows around the channel that there is produced in the channel a secondary circulation radially outwardly within the body of the stream and then radially inwardly, in which the stream during its passage around the channel is subjected to a radi