Papers by Keyword: Electroless Nickel

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Authors: Nor Bahiyah Baba, Mohamad Amir Harunsyam Lamshah, Mohamad Asyraf Mohd Amin
Abstract: The paper discussed on a 3-dimensional porosity network in electroless nickel (Ni) - yttria stabilized zirconia (YSZ) composite coating. The important characteristics of Ni-YSZ composite such as high ceramic YSZ incorporation and adequate porosity up to 40 vol.% are used as the main parameters. The arrangement of the porosity that give a 3-dimensional porosity network within the composite was design in Pro-Engineer Wildfire 3.0 software. Three structures of 3-dimensional porosity network were used namely honeycomb, atomic sphere and rhombic dodecahedra. The calculated area and volume of one unit porosity, consequently the number of porosity were compared between the three structures. These were supported by the porosity in the electroless Ni-YSZ composite coating obtained experimentally. Two batches were produced, EN-YSZ and EN-YSZ-G representing samples without and with pore former respectively. The two batch samples were investigated and compared. The addition of graphite pore former was burnt out completely and left porosity in the coating.
Authors: Anthony T.H. Beaucamp, Yoshiharu Namba, Richard R. Freeman
Abstract: Ultra-precision diamond turning can deliver very accurate form, often less than 100nm P-V. A possible manufacturing method for thin Wolter type-1 mirrors in hard X-ray space telescopes thus involves generating electroless nickel plated mandrels by diamond turning, before coating them with a reflective film and substrate. However, the surface texture after turning falls far short from the requirements of X-ray and EUV applications. The machining marks need to be removed, with hand polishing still widely employed. There is thus a compelling need for automated finishing of turned dies. A two step finishing method is presented that combines fluid jet and precessed bonnet polishing on a common 7-axis CNC platform. This method is capable of finishing diamond turned electroless nickel plated dies down to 0.28nm rms roughness, while deterministically improving form error down to 30nm P-V. The fluid jet polishing process, which consists of pressurizing water and abrasive particles for delivery through a nozzle, has been specially optimized with a newly designed slurry delivery unit and computer simulations, to remove diamond turning marks without introducing another waviness signature. The precessed bonnet polishing method, which consists of an inflated membrane rotated at an angle from the local normal to the surface and controlled by geometrical position relative to the work-piece, is subsequently employed with a novel control algorithm to deliver scratch-free surface roughness down to 0.28 nm rms. The combination of these two deterministic processes to finish aspheric and freeform dies promises to unlock new frontiers in X-ray and EUV optics fabrication.
Authors: Ya Xu Jin, Yu Ming Tian, Qiu Shu Li
Abstract: Electroless nickel plating with potassium titanate whisker was co-deposited on medium carbon steel substrates. The microstructure of the composite coatings was investigated. The effect of aging temperature on the microstructure of the composite coatings was studied using X-ray diffraction. The results indicate that the composite coatings will turn into crystal state with increasing heat treatment temperature. Experimental results also show that a maximum hardness is achieved for the composite coating after heat treatment at 400°C for 1 hour. The corrosion resistance and tribological properties of the composite coatings are not inferior to those of electroless Ni-P coating.
Authors: Véronique Vitry, Adeline Sens, Fabienne Delaunois
Abstract: Several electroless nickel deposits, on steel substrate, of varying chemistry were investigated in the as-plated and heat-treated condition: 3 nickel-phosphorous (low, mid and high P) and 2 nickel-boron (nickel-boron (lead) and nickel-boron (thallium)). Samples were characterized by SEM and X-ray diffraction. They were then submitted to Knoops microhardness testing and Taber abrasion tests, with abrasive CS-10 wheels, as well as scratch testing to investigate their mechanical properties and wear resistance. Hardness and wear resistance of all deposits were improved by heat treatment, but the best candidate was the Nickel-boron (lead), with a hardness over 1100 hk50 after heat treatment and a Taber Wear Index of 6. Scratch testing allowed identifying the damage mechanisms of the coated systems.
Authors: Cheng Hsun Hsu, Kuan Hao Huang, Yi Tsung Chen
Abstract: This study utilized electroless nickel (EN) and cathodic arc evaporation (CAE) technologies, with the known advantage of low processing temperature, to treat the austempered ductile iron (ADI) substrates. The eligibility of applying the EN and CAE-TiN duplex coatings on ADI, along with the coating properties, such as structure, roughness, adhesion, and surface hardness were evaluated and analyzed. Moreover, erosion tests were performed to further understand the effect of both the coatings on the erosive behavior of ADI. The results showed that the unique microstructure of ADI did not deteriorate after EN and CAE treatments. By the way of TiN/EN duplex coatings, surface hardness of ADI largely increased from 398 to 2243 HV5g. Moreover, the duplex coated ADI had a noticeable performance on erosion protection under a specific erosive environment with Al2O3 particles.
Authors: Hang Cui, Jian Dong Cui, Yao Hua Xu, Hao Zhou, Jun Du
Abstract: Nickel coated Zr-V-Fe non-evaporable getter (NEG) powders were prepared using electroless plating. The microstructure and composition of the Ni-coated Zr-V-Fe powders were analyzed by XRD, SEM and EDS. The hydrogen absorption performance of Ni-coated Zr-V-Fe powders and as-prepared powders were analyzed by dynamic method after an activation at 300°C for 2 hours. The hydrogen absorption performance of Ni-coated Zr-V-Fe powders and as-prepared powders at 100°C, 200°C, 300°C, 400°C, and 500°C were also analyzed. The results indicated that Ni existed as crystalline phase. The Ni coating played an important role as a catalyst which favored the dissociation of hydrogen on surface and Ni lowers the hydrogen diffusion energy for the Zr-V-Fe powders. The hydrogen absorption kinetics of Ni-coated Zr-V-Fe powders was improved in comparison with that of the as-prepared powders, and a relatively higher absorption rate was exhibited.
Authors: Sowjun Matsumura, Ju Sheng Ma
Authors: Nor Bahiyah Baba, Alan Davidson, Tariq Muneer
Abstract: Nickel ceramic composite have emerged as potential corrosion, wear and thermal resistance. The present work contemplates reinforcement of Ni-P deposits with YSZ ceramic by electroless nickel deposition technique. The ratio of metal nickel (Ni) to ceramic yttria stabilized zirconia (YSZ) in composite materials determines its ability in corrosion, thermal, wear resistance. The amount of porosity enhances thermal insulation. The 2k full factorials design of experiment and analysis of variance (ANOVA) were used in screening the EN composite process parameters for effective Ni-YSZ co-deposition for high ceramic incorporation and porosity level. A mathematical model was developed using piecewise linear regression analysis to predict the composition and porosity in terms of the EN Ni-YSZ composite coating process parameters. The models developed to predict the Ni composition and porosity in Ni-P-YSZ composite.
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