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The ability to co-deposit particulate matter in a matrix of electroless nickel has led to a new generation of composite coatings. Polycrystalline diamond is one of the many varieties of particulate matter that can be co-deposited. Composite diamond coating is a regenerative layer of diamond particles dispersed in a hard electroless nickel matrix. In this work, experiments have been carried out to study the effect of heat treatment on the wear characteristics of the electroless composite coating containing diamond particles. The results indicate substantial increase in wear resistance after heat treatment. For wear analysis, in order to overcome the difficulties in the most common 'weight loss' method, X-ray diffraction method is used. Also the concept of internal standard method of quantitative X-ray diffraction analysis with suitable modifications is employed for the study of removal of diamond particles from the matrix. Superior integrity of the diamond particles with the matrix of the coating is observed for the specimens when heat treated to around 350 �C because of the formation of phosphides. But increasing the heat treatment to about 500 �C affects the wear resistance. � 2008 Elsevier B.V. All rights reserved.

Electroless nickel (EN) coating is a well established surface engineering process that involves deposition of a metal-metalloid alloy coating on various substrates. The effect of surfactants on the surface roughness, microhardness and microstructure of electroless Nickel-Phosphorus (EN) surface protective coating obtained from an alkaline bath is presented in this paper. In this study the influence of surfactants sodium dodecylsulfate (SDS) and cetyl trimethyl ammonium bromide (CTAB) on the surface roughness, microhardness and microstructure of coated samples are investigated. EN deposits with addition of surfactant SDS and CTAB at a concentration of 0.6�g/l produce a smooth surface and the average roughness value (Ra) is 1.715�?m for SDS and 1.607�?m for CTAB which is less than the Ra value of EN deposit without surfactant addition (1.885�?m). The mean average roughness value (Ra) with addition of surfactant is 1.796�?m. It was found that without surfactant the micro hardness value of as-coated condition was 450�Hv. The micro hardness value increased to 685�Hv with addition of SDS and 675�Hv with addition of CTAB. The complete experimental details, results obtained and their analysis is presented in this paper. � 2008 Elsevier B.V. All rights reserved.

Electroless Nickel-Phosphorus deposits with phosphorus content of 4.35, 5.45, 6.80, 8.10 and 9.12 Wt.% P were made, on mild steel substrates. The deposits were annealed at 60, 100, 200, 300, 330, 360, 400 and 600°C for 2 hours. The crystallization process of these deposits was studied using X-ray line profile analysis, differential scanning calorimetry and microhardness. The X-ray diffraction pattern of all the deposits indicated the presence of crystalline and amorphous phases coexisting in the as deposited condition. The lattice disorder in the crystalline phase increased with increasing phosphorus content. Profile refinement techniques have been used to separate the crystalline nickel (111) reflection from the amorphous profile. The separated (111) and (222) profiles of nickel were used for crystallite size and microstrain analysis. The crystallite size of nickel was found to vary from 50A in the as deposited condition to about 600A in the fully annealed state (400°C). The crystallite size increased sharply above 300°C, indicating the onset of precipitation. The microhardness values showed typical precipitation hardening type of behavior, increasing from an initial value of about 450 VHN in the as deposited state to the peak hardness of about 825 to 950 VHN, corresponding to a temperature range of 360 to 400°C. Differential scanning calorimetry of these deposits, indicated only one major reaction between 325 to 375°C. Ni 3 P has been identified as the final stable precipitate at 600°C.

Electroless nickel-phosphorus (EN) deposits with and without addition of surfactants were made on mild steel substrates. Two surfactants namely sodium dodecylsulfate (SDS) and cetyltrimethyl ammonium bromide (CTAB) were used in the study. The EN coated samples were characterised using X-ray diffraction analysis and transmission electron microscopy. The XRD pattern of all the deposits indicated the presence of crystalline and amorphous phases coexisting in the as deposited condition. Profile refinement techniques have been used to separate the crystalline nickel (111) reflection from the amorphous profile. The crystallite size of nickel was found to vary from 200 nm in the as deposited condition to 80 nm with addition of surfactant. TEM study reveals a nano crystalline structure of the deposit in as plated condition and an amorphous structure with addition of surfactants. With addition of surfactants adhesion was good. The coating thickness varied from 12.7 ?m to 32.2 ?m with addition surfactants. Copyright � 2012 Inderscience Enterprises Ltd.

The effect of surfactants sodium dodecyl sulphate (SDS) and cetyltrimethyl ammonium bromide (CTAB) on the surface roughness, surface morphology and surface topography of electroless nickel (EN)-phosphorus surface protective coating obtained from an alkaline bath is presented in this paper. In this study the influence of surfactant concentrations on the surface roughness of coated samples were investigated. It was observed that the surface roughness, surface morphology and surface topography of Ni-P coating were clearly influenced by the addition of surfactants SDS and CTAB. EN deposits with addition of surfactant SDS and CTAB at a concentration of 0.6 g/l produce a smooth surface and the average roughness (Ra) value is 1.715 ?m for SDS and 1.607 ?m for CTAB which is less than the Ra value of EN deposit without surfactant addition (1.885 ?m). The mean average roughness (Ra) value with addition of surfactant is 1.796 ?m. EN deposit with addition of surfactants consists of a significant fraction of particles of nickel. In the presence of SDS, fine nickel particles have dispersed uniformly on the substrate surface resulting in smoother surface finish of the deposited layers. In the presence of CTAB, at lower concentrations (upto 0.6 g/l) coalescence of nickel particles have been deposited on the substrate surface and at the higher concentration (above 0.6 g/l) uniformly improved surface finish of the deposited layer is resulted. The complete experimental details, results obtained and their analysis are presented in this paper. � 2008 Elsevier B.V. All rights reserved.

The effect of surfactants on the surface roughness, hardness and microstructure of electroless nickel-phosphorus (ENi-P) coating obtained from an alkaline bath is presented in this paper. In this study the influence of surfactants such as Sodium Dodecyl Sulfate (SDS) and Cetyl Trimethyl Ammonium Bromide (CTAB) on the electroless Ni-P coated samples has been investigated. The variation on surface morphology was examined using Scanning Electron Microscope (HRSEM), surface roughness were measured using a stylus instrument and surface hardness were measured using a hardness tester. It was observed that the surface roughness, surface hardness and surface morphology of ENi-P coating were clearly influenced by the surfactants. Copyright � 2008, Inderscience Publishers.

In this work, the effect of process parameters such as stabilizer concentrations and plating bath temperature of the electroless Ni-P on efficiency and crystallinity are investigated. Both the nickel recovery and coating efficiencies are defined, quantified and analyzed by varying the above stated basic input process parameters. The integral breadth, crystallite size, microstrain and the relative proportions of amorphous and crystalline phases present in the coating are obtained using the X-ray diffraction technique and analysed. ? 2005 Elsevier B.V. All rights reserved.

The ability to co-deposit particulate matter in a matrix of electroless nickel has led to a new generation of composite coatings. Polycrystalline diamond is one of the many varieties of particulate matter that can be co-deposited. Composite diamond coating is a regenerative layer of fine diamond particles dispersed in a hard electroless nickel matrix. In this work, experiments have been carried out to study the effect of heat treatment, particle size and phosphorus content on the wear characteristics of the composite electroless coating containing diamond particles. The results indicate substantial increase in wear resistance after the coated sample containing 9-10 wt.%. P content having fine diamond particle size is annealed around 350�C. (C) 2000 Elsevier Science S.A. All rights reserved.The ability to co-deposit particulate matter in a matrix of electroless nickel has led to a new generation of composite coatings. Polycrystalline diamond is one of the many varieties of particulate matter that can be co-deposited. Composite diamond coating is a regenerative layer of fine diamond particles dispersed in a hard electroless nickel matrix. In this work, experiments have been carried out to study the effect of heat treatment, particle size and phosphorus content on the wear characteristics of the composite electroless coating containing diamond particles. The results indicate substantial increase in wear resistance after the coated sample containing 9-10 wt.%. P content having fine diamond particle size is annealed around 350 �C.

Electroless nickel-phosphorus coating has been deposited onto plain carbon steel specimens by using an alkaline bath based on NiCl2 as source of nickel cations. The tribological behaviour under dry non-lubricated conditions has been evaluated by employing the pin-on-disc test method. Two surfactants namely sodium dodecyl sulphate and cetyl trimethyl ammonium bromide were added to the EN bath for the first time in the similar kind of study. The influence of the surfactants on the hardness, friction and wear behaviour of the coatings was investigated and compared against the samples produced without addition of surfactants. Copyright � 2010 Inderscience Enterprises Ltd.