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Effect of heat treatment on microhardness of 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. 113, nr 1

5--12

EN

Purpose: The paper discussed the effect of heat treatment on electroless nickel-yttria-stabilised zirconia (Ni-YSZ) cermet coating. Ni-YSZ cermet coating has potential applications such as cutting tools, thermal barriers, solid oxide fuel anode, and various others. The compatibility of ceramic YSZ and metallic nickel in terms of the mechanical properties such as hardness by varying the heating temperature, time and ceramic particle size is highlighted. Design/methodology/approach: Ni-YSZ cermet coating was deposited onto a highspeed steel substrate using the electroless nickel co-deposition method. The temperature and time were varied in a range of 300-400°C and 1-2 hours, respectively. The microhardness measurements were carried out using a Vickers microhardness tester (Shimadzu) according to ISO 6507-4. The surface characterisation of the cermet coating was carried out using JOEL Scanning Electron Microscope (SEM) coupled with Energy Dispersive X-ray (EDX) JSM 7800F. The crystallographic structure of materials was analysed by X-ray diffraction (XRD) Bruker D8 Advance instrument. Findings: It was found that the microhardness of Ni-YSZ cermet coating with the ratio of 70:30, respectively, is directly proportional to the heating temperature and time. Heating the Ni-YSZ cermet coating at 300°C from room temperature (rtp) to 1 hour shows a 12% microhardness increment, while from 1 to 2 hours gives a 19% increment. Compared to heating at 350°C and 400°C, the increment is more significant at 33% and 49% for rtp to 1 hour and 8% and 16% for 1 to 2 hours, respectively. In addition, the effect of varying YSZ particle size in the Ni-YSZ cermet gave response differently for heating temperature and heating time. Research limitations/implications: The paper is only limited to the discussion of the heat treatment effect on Ni-YSZ cermet coating hardness property. The tribological effect will be in future work. Practical implications: The microhardness data may vary due to the Vickers microhardness force applied and the amount of ceramic particle incorporation and phosphorus content in the nickel matrix. Originality/value: The value of this work is the compatibility of the ceramic YSZ and metallic nickel matrix in terms of mechanical properties, such as hardness, upon heat treatment.

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Numerical investigation of biomass fast pyrolysis in a free fall reactor

Bieniek Artur, Jerzak Wojciech, Magdziarz Aneta

Archives of Thermodynamics

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2021

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Vol. 42, no 3

173--196

EN

This work presents two-dimensional numerical investigations of fast pyrolysis of red oak in a free fall reactor. The Euler–Lagrange approach of multiphase flow theory was proposed in order to describe the behaviour of solid particles in the gaseous domain. The main goal of this study was to examine the impact of the flow rate of inert gas on the pyrolysis process. Calculation domain of the reactor was made according to data found in the literature review. Volume flow rates were 3, 9, 18, and 25 l/min, respectively. Nitrogen was selected as an inert gas. Biomass pyrolysis was conducted at 550◦C with a constant mass flow rate of biomass particles equal to 1 kg/h. A parallel multistage reaction mechanism was applied for the thermal conversion of red oak particles. The composition of biomass was represented by three main pseudo-components: cellulose, hemicellulose and lignin. The received products of pyrolysis were designated into three groups: solid residue (char and unreacted particles), primary tars and noncondensable gases. In this work the impact of the volume flow rate on the heating time of solid particle, temperature distribution, yields and char mass fraction has been analysed. The numerical solutions were verified according to the literature results when the flow of nitrogen was set at 18 l/min. The calculated results showed that biomass particles could be heated for longer when the flow rate of nitrogen was reduced, allowing for a greater concentration of volatile matter.

3

Badania eksperymentalne prototypowej powietrznej pompy ciepła - studium przypadku

Dutkowski K.

Ciepłownictwo, Ogrzewnictwo, Wentylacja

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2017

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T. 48, nr 6

253--257

PL

W artykule przedstawiono wyniki badań prototypowej powietrznej pompy ciepła przeznaczonej do podgrzewania ciepłej wody użytkowej. Badaniom poddano pompę ciepła o mocy 4 kW. Badania zrealizowano w warunkach laboratoryjnych zgodnie z wytycznymi obowiązującej normy PN-EN 16147. Przedstawiono tylko te wyniki, które dotyczą Etapu A badań – Badanie czasu nagrzewania wody w zasobniku c.w.u. Z analizy uzyskanych charakterystyk wynika, że podczas procesu nagrzewania wody, prototypowa pompa ciepła pracowała niestabilnie. Kolejne badania, zrealizowane po wprowadzeniu rozwiązań modyfikujących działanie urządzenia, potwierdziły prawidłową pracę urządzenia. W efekcie zastosowanych modyfikacji czas nagrzewania wody użytkowej we współpracującym z pompą ciepła zasobniku o objętości 200 dm3 uległ skróceniu z ponad dziewięciu godzin do około pięciu godzin.

EN

The paper describes results of an experimental research of a prototype air heat pump designed to heat domestic hot water. The examined heat pump's power is 4kW. The experiment was performed under laboratory conditions and with accordance to the PN-EN 16147 Standard. Presented results are from the stage A (as defined in the Standard) and are about determination of time needed to heat water in the domestic hot water tank coupled with the heat pump. From the analysis of obtained results it is clear that the heat pump was not working in a stable fashion. Further research revealed that after certain modification of the device, its working parameters were stable. As a result of implemented modifications, the time to heat 200 dm3 of water shortened from nine to five hours.

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Porównanie cieplne łączników elektromagnetycznych nowych i eksploatowanych

Pawłot M.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 7a

309-311

PL

W artykule przedstawiono porównanie parametrów cieplnych łączników fabrycznie nowych i będących w wieloletniej eksploatacji. Badania dotyczyły pomiarów temperatury zestyku łącznika i spadku napięcia na mostku stykowym. W wyniku badań stwierdzono, że w trakcie eksploatacji zmienia się rezystancja zestykowa oraz warunki oddawania ciepła zdefiniowane kształtem krzywych nagrzewania.

EN

Thermal parameters of new switches and of the ones that have been operated for many years have been compared in the paper. The testing included measurements of temperature at switch contacts and voltage drop at contact junction. The testing has shown that operation processes bring about changes in contact resistance and heat-transfer conditions defined by the shape of heating curves.