Nickel blacks

Addition of an alkali metal hydroxide solution to an aqueous solution of a nickel(II) salt precipitates a finely-divided green powder. nickel(II) hydroxide NilOHfj on heating this gives the black oxide. NiO. which is also obtained by heating nickel(II) carbonate or the hydrated nitrate. Black nickel(II) sulphide, NiS, is obtained by passing hydrogen sulphide into a solution of a nickel(II) salt. 

Ma.nufa.cture. Several nickel oxides are manufactured commercially. A sintered form of green nickel oxide is made by smelting a purified nickel matte at 1000°C (30) a powder form is made by the desulfurization of nickel matte. Black nickel oxide is made by the calcination of nickel carbonate at 600°C (31). The carbonate results from an extraction process whereby pure nickel metal powder is oxidized with air in the presence of ammonia (qv) and carbon dioxide (qv) to hexaamminenickel(TT) carbonate [67806-76-2], [Ni(NH3)3]C03 (32). Nickel oxides also ate made by the calcination of nickel carbonate or nickel nitrate that were made from a pure form of nickel. A high purity, green nickel oxide is made by firing a mixture of nickel powder and water in air (25). 

Nickel sulfate also is made by the reaction of black nickel oxide and hot dilute sulfuric acid, or of dilute sulfuric acid and nickel carbonate. The reaction of nickel oxide and sulfuric acid has been studied and a reaction induction temperature of 49°C deterrnined (39). High purity nickel sulfate is made from the reaction of nickel carbonyl, sulfur dioxide, and oxygen in the gas phase at 100°C (40). Another method for the continuous manufacture of nickel sulfate is the gas-phase reaction of nickel carbonyl and nitric acid, recovering the soHd product in sulfuric acid, and continuously removing the soHd nickel sulfate from the acid mixture (41). In this last method, nickel carbonyl and sulfuric acid are fed into a closed-loop reactor. Nickel sulfate and carbon monoxide are produced the CO is thus recycled to form nickel carbonyl. 

Nickel Sulfamate. Nickel sulfamate [13770-89-3] Ni(S02NH2)2 4H2O, commonly is used as an electrolyte ia nickel electroforming systems, where low stress deposits are required. As a crystalline entity for commercial purposes, nickel sulfamate never is isolated from its reaction mixture. It is prepared by the reaction of fine nickel powder or black nickel oxide with sulfamic acid ia hot water solution. Care must be exercised ia its preparation, and the reaction should be completed rapidly because sulfamic acid hydrolyzes readily to form sulfuric acid (57). 

Nickel Salts and Chelates. Nickel salts of simple organic acids can be prepared by reaction of the organic acid and nickel carbonate of nickel hydroxide reaction of the acid and a water solution of a simple nickel salt and, in some cases, reaction of the acid and fine nickel powder or black nickel oxide. 

Black nickel oxide is used as an oxygen donor in three-way catalysts containing rhodium, platinum, and palladium (143). Three-way catalysts, used in automobiles, oxidize hydrocarbons and CO, and reduce NO The donor quaUty, ie, the abiUty to provide oxygen for the oxidation, results from the capabihty of nickel oxide to chemisorb oxygen (see Exhaust control, automotive). 

Nickel sulfides are very similar to those of cobalt, consisting of NiS2 (pyrites structure, p. 680), Ni3S4 (spinel structure, p. 247), and the black, nickel-deficient Nii-j S (NiAs structure, p. 555), which is precipitated from aqueous... 

Nickel is sometimes found in boiler deposits as nickel oxide, either in the gray-black nickel (-ous, -ic) oxide Ni304 form, or the black nickel sequioxide Ni203. Where present in the boiler, it usually originates from corrosion of condenser or preheater tubes. 

In addition, Lagowski and Simons showed (80) that the black, nickel-containing substances produced by the cocondensation of nickel atoms and alkynes are active, homogeneous catalysts for the oligomerization of terminal acetylenes under mild conditions. Table XVIII shows the yields of the oligomerization of propylene by these catalysts. 

Initially we tried the standard approach, reduction of NiL, NiB, or NiC with 2.0 equivalents of potassium in refluxing THF. Finely divided black nickel powders were obtained however, they showed rather limited reactivity toward oxidative addition with carbon-halogen bonds. Similar results were found for palladium and platinum. 

Several nickel salts are obtained by reactions of nickel oxide with mineral acids. Thus, the reaction of black nickel oxide with hot dilute sulfuric acid forms nickel sulfate, NiS04 6H2O. Similarly, dilute nitric acid, hydrochloric, and hydrobromic acids when heated react with the black form of nickel oxide to yield corresponding nickel salts as hexahydrates. 

Nickel sulfamate is prepared hy heating an aqueous solution of sulfamic acid, H2NSO3H, with fine nickel powder or black nickel oxide under controlled conditions ... 

Nickel sulfate can be made by several methods. It is prepared by dissolving nickel metal, its oxide, or its carbonate in sulfuric acid. In such methods, powdered metal or black nickel oxide is added to hot dilute sulfuric acid, or nickel carbonate is added to dilute sulfuric acid at ambient temperature ... 

Nickel oxide also comes in a black crystalline form that has a slightly higher oxygen content than its formula, NiO (Antonsen 1981). The nickel content of black nickel oxide is 76-77% compared with 78.5% for the more stable green nickel oxide. Nickel sulfate, nickel chloride, and nickel nitrate usually exist as hexahydrates, while nickel acetate is generally in the form of a tetrahydrate. 

Nickel has typical metallic properties it can be readily rolled, drawn into wire, forged, and polished. It is also ferromagnetic and a good conductor of both heat and electricity. Nickel is positioned after hydrogen in the electrochemical series and slowly displaces hydrogen ions from dilute hydrochloric and sulfuric acids. It reacts more rapidly with nitric acid. Nickel is highly resistant to attack by strong alkalis (Hawley 1981). Black nickel oxide readily yields nickel salts... 

For the less reactive, longer n-alcanols the activation of the nickel hydroxide electrode is necessary (Table 3). For that purpose several layers of black nickel oxide hydroxide are deposited on the electrode surface from a buffered nickel sulfate solution by changing the electrode polarity every 5-10 sec n.isb,20,21)... 

The 1,1-disubstituted hydrazine 53 a is rapidly oxidized in high yield to 54a at the nickel hydroxide electrode (Eq. (15), Table 17). The high reactivity of 53a can be seen from the dissolution of the black nickel oxide hydroxide deposit at the anode. 

Many of the finishes applied to other types of metal products can also be applied to zinc die castings, although some differences in formulation as well as occasional differences in method of application may be desirable. The types of finishes applicable to zinc die castings include mechanical finishes (buffed, polished, brushed, and tumbled) electrodeposited finishes (copper, nickel, chromium, brass, silver, and black nickel) chemical finishes (chromale, phosphate, molybdate and black nickel) and organic finishes (enamel, lacquer, paint and varnish, and plastic finishes). Electrodeposited coatings of virtually any metal capable of electrodeposition can be applied to zinc die castings. 

Figure 8.7 Structure of CaNiN. An example of a calcium containing ternary nitride containing linear Ni-N chains. Small white = Calcium, Black = Nickel, Large white =...

Four main types of antioxidants are commonly used in polypropylene stabilizer systems although many other types of chemical compounds have been suggested. These types include hindered phenolics, thiodi-propionate esters, aryl phosphites, and ultraviolet absorbers such as the hydroxybenzophenones and benzotriazoles. Other chemicals which have been reported include aromatic amines such as p-phenylenediamine, hydrocarbon borates, aminophenols, Zn and other metal dithiocarbamates, thiophosphates, and thiophosphites, mercaptals, chromium salt complexes, tin-sulfur compounds, triazoles, silicone polymers, carbon black, nickel phenolates, thiurams, oxamides, metal stearates, Cu, Zn, Cd, and Pb salts of benzimidazoles, succinic acid anhydride, and others. The polymeric phenolic phosphites described here are another type. 

Nickel(IV) is also known, but this oxidation state appears to be confined to the red salt, K2NiF6, the black nickelate, K2Ni03, and a number of rather exotic complexes. 

Annabergite. Black nickel. Blueite. (See Nickel ochre) (See Nicomelane) NiSj.l2FeS, 4-2 3-5 ... 

The stable nickel(II) salts are derived from nickel(II) oxide, NiO, which is a green substance. The dissolved nickel(II) salts are green, owing to the colour of the hexaquonickelate(II) complex [Ni(H20)6]2 + in short however, this will be regarded as the simple nickel(II) ion Ni2+. A brownish-black nickel(III) oxide Ni203 also exists, but this dissolves in acids forming nickel(II) ions. With dilute hydrochloric acid this reaction yields chlorine gas ... 

The green nickel(II) hydroxide precipitate can be oxidized to black nickel(III) hydroxide with sodium hypochlorite solution ... 

If the solution of tetracyanonickelate(II) is heated with sodium hypobromite solution (prepared in situ by adding bromine water to sodium hydroxide solution), the complex decomposes and a black nickel(III) hydroxide precipitate is formed (difference from cobalt ions) ... 

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