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The high capacity and fast response of Moog electrohydraulic flow control valves has allowed a difficult test specification to be met at low cost. The two Moog Series 60 valves are fitted to a hydraulic test rig in British Airways' engineering centre at Heathrow Airport, London.

Geigy Co. Ltd. Stand 75. Diversified application of benzotriazole as a corrosion inhibitor specifically for copper and its alloys is the main theme of Geigy's stand.

In this paper, wear of the cylinder is taken to mean not only wear of the liner but of the piston ring assembly also, since usually, though not always, the wear of the one is closely related to that of the other. The wear process may be corrosive, abrasive or frictional, and it is likely that all three processes occur together to varying extents, depending on such factors as engine design and operating conditions.

The purpose of the investigation was to research the best process of electroless nickel (EN) plating on AZ91D magnesium alloy and the performance of EN plating coating.

Through single factor test and orthogonal test, EN plating on AZ91D magnesium alloy was researched. The plating rate and porosity were analyzed. The coating appearance of EN plating coating and magnesium alloy substrate was evaluated. The electrochemical properties of EN plating coating and substrate were researched using electrochemical workstation, and their compositions and structure were examined using X-ray diffraction and scanning electron microscopy.

The results made by combination of experimental and orthogonal test showed that the best formula of EN plating was 8.8 g·L⁻¹ nickel ion, 25 g·L⁻¹ lactic acid, 28 g·L⁻¹ reducing agent, 1.8 ml·L⁻¹ corrosion inhibitor, 1 mg·L⁻¹ stabilizer, temperature at 85°C and pH value at 5.5. The plating was uniform, dense and with no cracks. The electrochemical tests showed that the corrosion resistance of EN plating was better than that of magnesium alloy substrate.

The results indicated that the corrosion resistance of magnesium alloy improved markedly after EN plating at the best formula and the plating covered magnesium alloy completely.

CHROME PLATING Cathodic potential in make‐and‐break of polarisation current. In order to understand the mechanism of electro‐deposition of metals considerable importance attaches to the study of cathode potential changes observable in the short interval of time between switching on or off of the polarisation current, especially with chromium, as previous Russian workers have noted (literature references are mainly Russian). But these do not satisfactorily explain all the observed phenomena. This is here attempted by means of oscillographic recordings of cathode potential changes, as per method described, using a bath containing (g./l.): 250 CrO3 and 5 H2SO4. Micro‐photographs are given of the oscillograms and of chromium structure. It is shown that, on switching in the current, a cathodic film is formed which is adsorbed on the surface. This proceeds the more quickly the greater the current density and higher the temperature, also the lower the sulphate concentration. With rise in temperature there is more interaction between the film formed and the chromium deposit, depending on the structure of this latter. Under the most widely used conditions in general practice it is concluded that the film formation is almost instantaneous when the current is switched on and intimate interaction thereof with the cathode surface. Ten references.— (M. A. Shluger, Zh. prikl. Khim., 1960, 33 (6), 1355–1359.)

FACTS ABOUT STAINLESS STEEL. THE ignorance which exists in the mind of the public concerning elementary facts about stainless steel was brought to our notice when we learnt that it is generally and genuinely believed by a large number of our 45 million people that ‘stainless’ is a plating substance, and pots and pans made of other metals can quite easily get ‘the treatment’! Yet Great Britain is the world's second largest producer of stainless steel.

Discusses the need to combat wear and corrosion, and to analyse wear types with regard to weight, longer working life, demands on performance, etc. Provides details of various surface coatings and debates their properties. Examines several R&D programmes on new‐generation coatings. Concludes that surface‐coating engineers should be part of the design team in the manufacturing process.