Ni-P alloy

Figure 4. DSC traces for three bulk glassy Pd-Ni-P alloys at the heating rate of 20 K/min.

The calculated Debye temperatures are also listed in Table 3. From this table, it is clear that the elastic properties of the bulk amorphous Pd-Ni-P and Pd-Cu-P alloys change little with changing composition. The elastic moduli of the Pd-Cu-P alloys are slightly lower than those for the Pd-Ni-P alloys. 

The corrosion rate of amorphous Ni-P alloys in 1 n HCl is lower than those of crystalline nickel metal and amorphous Fe-P-C alloy by factors of about 5 and 250, respectively, and is further decreased by the addition of various elements (Fig. 3.73). 

Fig. 3.73 Average corrosion rates of amorphous Ni-P alloys measured in 1 n HCl at 30°C. Included are average corrosion rates of crystalline nickel and nickel-base alloys ...

Note that essentially the same behavior as for the Ni-P alloy deposition was observed in electrodeposition of other iron-group alloys, such as Co-W and Ni-W alloys. Namely, the deposition current in the presence of Na2W04 (the W-source of the Co-W and Ni-W alloys) started to flow at a more positive potential than in the absence of Na2W04, indicating that the electrodeposition of the Co-W and Ni-W alloys occurs by essentially the same mechanism as that of the Ni-P alloy, suggesting the presence of a general mechanism for the induced co-deposition of these alloys. 

Figure 14.4 (a) Current density vs. potential curves obtained for electrodeposition of Ni-P alloy in the presence (solid curve) and absence (dashed curve) of NaH2P02 (P-source of the alloy). 

Nickel phosphorus (Ni-P) alloy deposition, 9 691-693. See also Ni-P entries Nickel phosphorus compounds, 17 124... 

Ni-P adhesion, 9 705. See also Nickel phosphorus entries Ni-P alloys, solderability, 9 707, 708 NIPAm hydrogels, 13 738 Ni-P density, 9 705 Ni-P electrical resistivity, 9 706 Ni-P ferromagnetic properties, 9 706 Nipkow disk, 16 484 Ni-P mechanical properties, 9 706 Niranium N/N, base-metal dental alloy, 8 309t... 

After fixing Pd catalyst on modified nylon 12 surfaces by various methods, they were coated by electroless Ni-P alloy plating. Alumina- or silica-modified nylon 12 was well wet by electroless plating liquid, and modified nylon 12 situations in a liquid were good dispersed. Nickel metal was deposited on silica or alumina surface. Finally, it was confirmed that the formation of metal layer was depended mainly on the method of Pd catalyst fixing. 

The engineering properties of electroless nickel have been summarized (28). The Ni—P alloy has good corrosion resistance, lubricity, and especially high hardness. This alloy can be heat-treated to a hardness equivalent to electrolytic hard chromium [7440-47-3] (Table 2), and the lubricity is also comparable. The wear characteristics are extremely good, especially with composites of electroless nickel and silicon carbide or fluorochloropolymers. Thus the main applications for electroless nickel are in replacement of hard chromium (29,30). 

Furthermore, this technique allows variation of the grain size [30-33] this is important because many chemical and physical properties of nanostructured materials depend on the grain size. Only by variation of the crystallite size - this is a novd aspect in materials sdence and technology [34] - is it possible to tune and hopefully improve certain physical properties of one and the same material for example, the enhanced hardness of nano-Au, the toughness of nano-Ni/P alloys [35], the soft magnetic properties of nano-Ni [36] and the resistance of nanostructured materials [37, 38] promise industrial applications [39-41],... 

Sect. 3.6.8). Most magnetic thin-film layers are electroless Co(P) and Co—Ni(P) alloys. Overcoat is a bilayer consisting of Si02 and a lubricant. 

Electroless deposition of Ni-P alloys using hypophosphite as a reducing agent ... 

At the metallic surface, due to codeposition of other elements (e.g., P, B, or similar) as seen on the examples of Ni-P or Ni-B alloys, formation of hydrolyzed species may occur. This is illustrated by the equation (15) for the example of codeposition of Ni-P alloys. The hydroxides or other hydrolyzed species which are formed as intermediates can further be reduced to the metallic state in the presence of the reducing agent. 

Electroless deposition of thin films of Ni-P alloys has found numerous applications in many fields due to their excellent corrosion resistance, high wear resistance, high hardness, and acceptable ductility. 

It was applied first to describe the electroless deposition of Ni-P alloys, and later for electroplating of alloys of W and Mo with the iron-group metals. 

In the following text, we will present the data on catalytic hypophosphite oxidation on nickel using deuterium tracer and online electrochemical mass spectrometry studies of partial reactions and their mutual interaction as a function of electrode potential, the modeling of the catalyst surface state upon the oxidation of hypophosphite, isotopic gas composition during electroless Ni-P alloy... 

Significantly low defectiveness as compared to one-layer photomasks (pore-free films are obtained) since as a rule, the centers of lower Si layer crystallization do not coincide with the centers of upper Ni-P alloy layer crystallization transparent defects, pin holes and holes in the upper layer of Ni-P alloy are not continuation of transparent defects, pin holes and holes in the lower layer of Si. 

High wear-resistance obtained as a result of annealing of Ni-P alloy and formation of hard intermetallic (NijP) substance. 

B ribbon was explained as increasing the concentration of electron-deficient nickel species (37). Moreover, as other studies revealed, the electronic state of nickel in Ni-P alloys depends on the ratio of the alloying elements (145). In alloys with 75% or more nickel, P donates electrons to nickel, whereas with lower percentages of nickel, P accepts electrons and forms electron-deficient nickel. This demonstrates that changes in the local surface concentrations that result from pretreatment can alter the electronic states of the active species. Similar changes might take place also as a result of the action of the reactant. Full interpretation of data different from previous results on X-ray amorphous and crystalline Ni-B (146-148) and Ni-P (146-150) as well as the correlation of observations on amorphous Ni-B prepared by different methods (141, 142, 144) requires further examination. 

It can be seen that the activities of the amorphous alloys are lower than those of the polycrystalline catalysts. Formation of the corresponding diol was not observed on the amorphous catalysts, while the crystalline catalysts either produced the diol selectively, or a mixture of the diol and the hydroxy ketone was formed. The fundamental reason for the lower activity and higher selectivity of the amorphous alloys is their rather small surface area. Of the amorphous alloys studied, Ni-B and Ni-P alloy powders prepared by chemical reduction exhibited higher activities than those of Ni-P alloys prepared by electrolytic reduction or rapid quenching. This difference in activity can be attributed to an oxide layer covering the surface of m-P foils [Ij. It is necessary to point out, however, that the comparison of activities is based on unit catalyst weight. Obviously, this comparison does not take into account the real surface area of the nickel samples, nor active site densities. 

The bulk amorphous alloys were prepared by two synthesis methods. To prepare the Pd-Ni-P alloys, commercial Ni2P powder (99.5% pure) was arc melted imder a purified argon atmosphere to produce M2P ingots. Then, solid M2P, palladium (99.99% pure), and nickel (99.99% pure) were arc-melted to form alloy ingots of the desired composition. These alloys were placed in fused silica tubes, and repeatedly purified in molten B2O3, as described in Refs. [6,7]. Finally, the fused silica tubes containing the melt and the flux were quenched in water. 

---