Chemical deposition of hard composite coatings Ni–Cu–P–Cr2O3

The technological (deposition rate, coating composition) and functional (surface roughness, microhardness) characteristics of chemical composite coatings Ni—Cu—P—Cr2O3 obtained from weakly acidic and slightly alkaline solutions are compared. It is shown that coatings deposited from slightly alkaline solution contain slightly less phosphorus and chromium oxide than coatings deposited from weakly acid solution (2...3 % wt. phosphorus and up to 3.4 % wt. chromium oxide), formed at higher rate (24...25 microns per 1 hour of deposition at temperature of 80 °C), are characte rized by lower roughness and increased microhardness. The Vickers microhardness at 0.05 N load of composite coatings obtained from slightly alkaline solution and heat-treated at 400 °C for 1 hour is 13.5...15.2 GPa, which is higher than values for coatings deposited made of weakly acidic solution. The maximum microhardness of coatings is achieved at concentration 20 g/l of Cr2O3 particles. The technology of chemical deposition of Ni—Cu—P—Cr2O3 coatings formed in slightly alkaline solution is promising for obtaining of materials with increased hardness and wear resistance.

A TYPE SPECIFIC SUBSTANCE DISTINCT FROM THE SPECIFIC CARBOHYDRATE IN PNEUMOCOCCUS TYPE I

1. Evidence has been presented for the existence of a substance distinct from the specific carbohydrate in the autolytic products of Pneumococcus Type I. 2. The substance reacts specifically by precipitating homologous antiserum which either occurs naturally without antibody against the specific carbohydrate or has been deprived of that antibody artificially. 3. In guinea pigs passively sensitized with such antisera the homologous autolysate containing the substance alone produces typical lethal anaphylactic shock. 4. In weakly alkaline solution the substance is destroyed by boiling. In weakly acid solution it resists a temperature of 100°C. for at least ½ hour. Autoclaving for 1 hour at 15 pounds pressure in either acid or alkaline solution destroys its activity as precipitinogen. 5. The substance is resistant to peptic digestion. 6. The chemical nature and the possible identification of the substance as a haptene have been discussed.

VI.—The Precipitation of Salts by the Corresponding Acids

It is well known that salts such as the chlorides of the alkali metals are less soluble in water containing the corresponding acid than in water alone; and for sparingly soluble salts, in weakly acid solution, the decrease of solubility has been shown to follow quantitatively the course predicted from simple ionic notions. With concentrated solutions of strong electrolytes, however, the causes which operate are still obscure; and, indeed, much has yet to be discovered as to the facts in such cases. There may be said to be two methods of studying the isothermal phenomena in question. The first, which has received attention from numerous observers, consists in determining the solubility of a salt in water containing the acid in varying concentrations. This may be termed the “solubility“ method. The second method seeks to ascertain the minimum concentration of aqueous acid which must be used in order to cause deposition of salt, when the acid is added in small quantity to the saturated aqueous salt solution. This we shall refer to as the “precipitation“ method; it was adopted by Gibson and Denison, and formed the subject of a communication by them to this Society (Proc., vol. xxx., 1910, p. 562).