Nickel Boron

Hydrazine—borane compounds are made by the reaction of sodium borohydride and a hydrazine salt in THF (23,24). The mono-(N2H4 BH ) and di-(N2H4 2BH2) adducts are obtained, depending on the reaction conditions. These compounds have been suggested as rocket fuels (25) and for chemical deposition of nickel—boron alloys on nonmetallic surfaces (see Metallic COATINGS) (26). 

The majority of ah these classes, even noneutectic ahoys, have been processed successfuhy by rapid solidification technology. This technology provides a beneficial alternative in the form of a flexible ductile foh when materials that are inherently brittle are used. Examples are the nickel—boron—shicon ahoys and many others, when produced using conventional technology (5). 

Electroless nickel—boron baths use sodium borohydride or dimethylamine borane [74-94-2] in place of sodium hypophosphite (see Boron compounds). The nickel—boron aHoy is brittle, highly stressed, and much more expensive than nickel—phosphoms aHoys. Nickel—boron is mainly used to replace gold in printed circuit board plating. 

Multilayer boards, which use multiple interior laminates of plastic and copper, now comprise over half of the value of production, though much less on a surface area basis. Surface mount technologies demand extreme flatness and reproducibiHty from surfaces. Greater packing density has led to commercial production of finer lines and holes, often less than 50 p.m and 500 p.m, respectively. Electroless gold over electroless nickel—phosphoms, or electroless nickel—boron alone, is often used as a topcoating for wire bonding or improved solderabiHty. 

A common constituent of salt baths is boric oxide and the use of such mixtures in contact with nickel-rich alloys containing Ti, A1 or other strong reducing elements is to be avoided, owing to the possible formation of a nickel-boron eutectic of low melting point. 

In recent years, the spraying process has been adapted for hard facing, using the chromium-nickel-boron alloys which have become known as Colmonoy. More recently still, the cobalt-base Stellite alloys have also been used. These materials in powder form are sprayed on to the surface in the usual way. The deposit is afterwards heat treated by a torch, so that fusion takes place. The process is often known as spray-welding. Such coatings are primarily used for hard facing under wear conditions, but as the Anal surface is nickel-chromium or cobalt-chromium they exhibit very high anticorrosive properties. 

Electroless nickel-phosphorus should not be used with either fused or hot, strong, aqueous caustic solutions because the coating offers lower resistance to attack than does electrodeposited nickel. As-deposited electroless nickel-boron, however, offers good resistance to hot aqueous caustic solutions It is also resistant to solutions of oxidising salts such as potassium dichromate, permanganate, chlorate and nitrate. 

Heat treatment, e.g. 2 h at 600°C, improves the resistance to corrosion of nickel-boron and nickel-phosphorus electroless nickel deposits, especially to acid media. This presumably results from formation of a nickel-iron alloy layer . 

Nickel barium titanium primrose priderite, formula and DCMA number, 7 347t Nickel-based alloys, properties of, 77 848t Nickel-base superalloys, 77 103 Nickel battery technology, 77 111 Nickel-beryllium alloys, 3 656-659 Nickel-boron deposition, 9 693-695, 708 Nickel brass, corrosion, 7 812 Nickel bromide, 77 110... 

Recently, silica supported nickel-boron catalyst was tested in the hydrogenation of cyclopentadiene and was found to be selective in giving cyclopentene47. 

Kudryavtsev V.N., Makkaveyeva S., Pilipenko D.G. (2001) Electrodeposition of nickel and nickel-boron alloy from ammonia-citrate bath, Galvanotechnique and surface treatment 4 (9), 25-30. 

Zvyagintseva A.V., Falytcheva A.Y. (1997) Physico-mechanical properties of nickel-boron coatings, Galvanotechnique and surface treatment 2 (5), 24-31. 

Zvyagintseva A.V., Kravtsova Y.G. (2004) The comparative characteristic of electrochemically received nickel and nickel-boron films hydrogen permeation. Proc. 4 Int. Conf. VOM-2004, Donetsk, 415-420. 

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