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1

Parametric optimisation of microhardness on heat-treated electroless Ni-YSZ cermet coating

Bahiyah Baba N., Ghazali A. S., Abdul Rahman A. H., Sharif S

Journal of Achievements in Materials and Manufacturing Engineering

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2022

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Vol. 112, nr 1

33--41

EN

Purpose: The paper discusses the parametric optimisation of the electroless Ni-YSZ cermet coating microhardness upon heat treatment. Heat treatment is a process to increase the mechanical properties of the electroless nickel coating and it can be enhanced by manipulating its parameters. Parametric optimisation is conducted by the design of experiment full factorial 3x3 with 27 runs. Treating temperature, treating time and ceramic particle size parameters at 3-level are evaluated using statistical tool ANOVA in Minitab20. Design/methodology/approach: Ni-YSZ cermet coating is deposited onto a high-speed steel substrate using the electroless nickel co-deposition method. The temperature and time were varied in a range of 300-400°C and 0-2 hours respectively. The microhardness measurements were carried out using a Vickers microhardness tester (Shimadzu) according to ISO 6507-4. The surface characterisation was analysed using Cambridge Stereoscan 90 Scanning Electron Microscope (SEM) coupled with Energy Dispersive X-ray Analysis (EDXA). Findings: The optimum condition in obtaining high microhardness on Ni-YSZ cermet coating is evaluated by statistical tool ANOVA in Minitab20 software. It is found that the most significant parameter for high microhardness is at the treating temperature of 400°C followed by treating time at 2 hours using nano-sized YSZ particles. The ceramic particle size is found not a significant parameter in obtaining a high microhardness, however it has effect on interaction between treating temperature and treating time. Research limitations/implications: The paper only limits to the optimisation condition of microhardness on Ni-YSZ cermet coating hardness property by varying heat treatment parameters. Practical implications: The optimisation condition obtained might only applicable to the electroless Ni-YSZ cermet coating with similar electroless nickel solution and treatments. Originality/value: The value of this work is the heat treatment parametric optimisation to obtain high microhardness on electroless Ni-YSZ cermet coating by using the design of experiment 3-level full factorial.

2

Development of Electroless Ni-P Coatings on Sisal Fiber

Hemachandran R., Pugazhvadivu M., Jayabal S.

Fibres & Textiles in Eastern Europe

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2017

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Vol. 25, no. 1 (121)

32--35

EN

Improving the properties of natural fibers can be interesting from a technological point of view. Modifications can result in a high specific strength, electromagnetic interference (EMI) shielding, antistatic brush etc. Plant fiber composites would make them an option for use in components such as rifle stocks and knife handles etc. The greatest challenge would be to ensure that the components are all weather capable, but today several materials exist that have a high moisture tolerance. Moreover with proper surface coating techniques, most natural fibers materials can be toughened up to use as reinforcement. An attempt was made using a proprietary experimental set-up to coat natural fiber with electroless nickel phosphorus (ENi-P), since sisal fiber is a non-conducting material. In this article the surface morphology, ingredients and cross-section images of the modified natural fibers were characterised by a scanning electron microscope equipped with EDAX.

PL

Poprawa właściwości włókien naturalnych jest interesująca z technologicznego punktu widzenia. Wynikiem modyfikacji może być wysoka wytrzymałość, poprawa ekranowania pól elektromagnetycznych (EMI), poprawa właściwości antystatycznych itp. Powłoki niklowo-fosforowe na włóknach roślinnych umożliwiają wytworzenie różnego rodzaju kompozytów, min. o powierzchni odpornej na wilgoć. Morfologia powierzchni kompozytów była badana za pomocą SEM-EDAX.

3

Adhesivity of electroless Ni-P layer on austenitic stainless steel

Smoljan B., Iljkić D., Maretić M.

Archives of Materials Science and Engineering

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2016

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Vol. 80, nr 2

53--58

EN

Purpose: Optimization of testing of adhesivity of electroless deposited nickel-phosphorous coatings on austenitic stainless steel substrate. Design/methodology/approach: The main study has been focused on comparison of testing methods of adhesivity of electroless nickel-phosphorous coatings and analyses of influence of heat treatment on adhesivity of electroless nickel-phosphorous. Findings: It was found out that adhesivity of electroless nickel-phosphorous coatings can be successfully characterized by Vickers hardness tester. Research limitations/implications: The study was not extended to other types of deposited layers in order to be able to bring a general decision about applicability of this method in the testing of adhesivity of deposited layers. Practical implications: Based on experimental results it was found out that heat treated nickel-phosphorous coating have higher microhardness than non-heat treated electroless nickel-phosphorous coatings. High microhardness of heat treated nickel-phosphorous coating is connected with formation of Ni3P phase. Moreover, better adhesivity can be achieved by application of proper activation process before electroless coating. Originality/value: Standard Vickers hardness method was successfully applied in testing of adhesivity of electroless nickel-phosphorous coatings on austenitic stainless steel substrate.

4

Bezprądowe cynowanie miedzi z roztworów tiomocznikowych

Araźna A., Kozioł G., Gromek J., Bieliński J.

Przegląd Elektrotechniczny

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2014

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R. 90, nr 9

9-11

PL

W pracy dyskutowana jest zależność pomiędzy szybkością procesu immersyjnego cynowania i warunkami prowadzenia tego procesu, takimi jak stężenie kwasu i tiomocznika w roztworze do cynowania na bazie soli chlorkowej (SnHCl) lub soli metanosulfonianowej (SnMSA). Oceniana jest również lutowność warstw Sn. Wyniki eksperymentów wykazują znaczący wpływ stężenia tiomocznika i kwasu na szybkość procesu cynowania, niezależnie od typu roztworu do cynowania. Szybkość osadzania warstw Sn wzrastała ze wzrostem tiomocznika w roztworze. Natomiast szybkość cynowania początkowo rosła, a następnie malała ze wzrostem stężenia kwasu w roztworze. Lutowność badanych warstw bezpośrednio po ich wykonaniu była bardzo dobra lub dobra. Zwilżalność starzonych termicznie warstw cyny przez pastę lutowniczą była gorsza niż warstw w stanie dostawy i zależała od grubości warstw i typu roztworu, z którego były one osadzane. Różnica w lutowności warstw przypisywana była różnicy w ich strukturze i strukturze związków międzymetalicznych.

EN

In the presented work, the correlation between the immersion Sn coatings deposition rate and the deposition conditions, such as concentrations of acid and thiourea, from immersion tin plating solution based on hydrochloric (SnHCl) salt or methanesulphonic (SnMSA) salt, is discussed. The solderability of tin coatings is also tested. The experiment results show the significant influence of the thiourea and acid concentration on the Sn deposition rate irrespectively of the type of solution. The deposition rate increases with increased concentration of thiourea. However, the deposition rate first increased and then decreased with the increase in acid concentration. The solderability of as-deposited coatings was good or very good. The wettability of thermally aged tin coatings by the solder paste was worse than for as-deposited coatings and depended on the thickness and type of bath. It is being assigned to the difference in the structure of tin layers and intermetallic grains.

5

Fundamentals on inorganic membranes: present and new developments

Larbot A. B.

Polish Journal of Chemical Technology

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2003

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Vol. 5, nr 2

8-13

EN

The classical methods for preparing ceramic membranes from macroporous support to microporous or dense layers, as extrusion, suspended powder method, sol-gel processes, will be described. But other techniques are also used as chemical vapour deposition or electroless for dense or microporous membranes, hydrothermal treatment to elaborate zeolite layers will be also described. Hollow fibers, a new configuration for ceramic membranes will be presented.