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Titanium has certain properties that make it an ideal material to prevent wear; titanium alloys lend themselves to a versatility of mechanical properties by heat treatment. This should provide a sound tribological combination but, unfortunately, these materials can cause serious galling and fretting. The authors describe the properties of titanium and its alloys, methods of forming and lubricating them and possible methods of combatting wear. In the second part, in our next issue, they will deal with diffusion, electrodeposition, electroless deposition of metallic coatings, and other ways of preventing fretting. In both parts an extensive review of published literature is made and all bibliographical references will be included in our next issue.

Bulk samples, of the order 0.2 mm thick, of cobalt-phosphorus alloys have been prepared by prolonged electroless deposition with phosphorus contents varying from 5 to 9 at%. Alloys with less than 8.8 at% were found to be crystalline with a single-phase h.c.p. structure, and those with 9 at% were amorphous. The saturation magnetization, magnetostriction, coercivity, and susceptibility of the crystalline alloys varied uniformly with phosphorus content. The amorphous alloys had significantly different magnetic properties from the crystalline ones of similar composition; in particular the susceptibility was nearly two orders of magnitude greater. This greater susceptibility was predominantly associated with the absence of magnetocrystalline anisotropy in the non-crystalline material. On annealing, the amorphous material first transformed to a single-phase h.c.p. structure similar to that of the crystalline alloys, and at a higher temperature to the equilibrium two-phase structure of a cobalt-rich h.c.p. phase and an orthorhombic Co2P phase. The susceptibility of the amorphous alloy fell by a factor of 15 times on annealing. This was attributed to the introduction of crystalline order and hence magneto-crystalline anisotropy. Massive Proben von Kobalt-Phosphorlegierungen mit einer Dicke von der Grosenordnung 0,2 mm wurden durch fortgesetzte elektrodenlose Auftragung hergestellt, wobei der Phosphorgehalt zwischen 5 und 9 % variierte. Es wurde gefunden, das Legierungen mit weniger als 8,8 at% in einer einzigen kristallinen Phase mit h.d.p.-Struktur kristallisieren und die mit 9 at % amorph sind. Die Sattigungsmagnetisierung, Magnetostriktion, Koerzitivkraft und Suszeptibilitat der kristallinen Legierungen andern sich gleichmasig mit dem Phosphorgehalt. Die amorphen Legierungen zeigten betrachtlich unter-schiedliche magnetische Eigenschaften gegenuber kristallinen Legierungen ahnlicher Zusammensetzung; insbesondere war die Suszeptibilitat um nahezu zwei Grosenordnungen groser. Diese grosere Suszeptibilitat war vorwiegend mit dem Fehlen magnetokristalliner Anisotropie im nichtkristallinen Material verbunden. Bei einer Temperung ging das amorphe Material zuerst in eine einphasige h.d.p.-Struktur uber, die der der kristallinen Legierung ahnlich ist, und bei einer hoheren Temperatur in die Gleichgewichts-Zwei-Phasen-Struktur, eine Kobalt angereicherte h.d.p.-Phase und eine orthorhombische Co2P-Phase. Die Suszeptibilitat der amorphen Legierung ging um den Faktor funfzehn nach der Temperung zuruck. Dies wurde der Einfuhrung einer kristallinen Ordnung und damit einer magneto-kristallinen Anisotropie zugeschrieben.

–A short history of electrodeposited magnetic films is presented from the early work at the turn of the century to the latest reported work in hypophosphite ion containing solutions. A short summary of magnetic terms and a preliminary look at the electroless deposition of magnetic films is also included.

Ultraviolet light has been shown to be effective in inhibiting the electroless deposition of Cu, Ni, and Co if applied after sensitization, and of Ni and Co after activation. Electron microscopic techniques are applied to investigate these phenomena. It is concluded that structural changes in the sensitizing and activating agents induced by the u.v. light are connected with the inhibition of metal deposition.

Composites of randomly oriented, chopped carbon fibres in Pb, Ag, Cu, Ni and Co have been prepared by powder metallurgical techniques, with fibre contents up to 25 vol.%. The most satisfactory method of fabrication is hot-pressing of fibres precoated with metal by electroless deposition. Rates of wear of the composites, measured at room temperature during sliding against tool steel with and without lubrication, are appreciably lower than those of the parent metals. The coefficients of friction are not reduced, however, nor are the wear rates at elevated temperatures (470°C). It is concluded that the carbon fibres function by facilitating the development of a strengthened surface layer during sliding. The fibres do not appear to improve the bulk mechanical properties and possible reasons for this are discussed.

Nickel and copper have been deposited on medium modulus carbon fibre tows using an electroless technique. Copper was deposited by a method which could probably be developed into a continuous process. Difficulties were experienced in covering the fibres at the centre of 5000 filament tows. The effects of spreading and altering the tension of the fibres and of altering the speed of flow of the reagent past the fibres have still to be studied.