Structural, mechanical and tribological characterization of chromium oxide thin films prepared by post-annealing of Cr thin films

Khojier, K.; Savaloni, Hadi; Ashkabusi, Z.; Dehnavi, N. Zare

doi:10.1016/j.apsusc.2013.07.123

Cited by 37 publications

(17 citation statements)

References 29 publications

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“…In order to overcome these problems, many studies have been carried out to limit formaldehyde emissions and resin-bond improvement (STOCKEL et al, 2012;VALENZUELA et al, 2012;MENDES et al, 2013). Heat-transferring property of metal nanoparticles (KHOJIER et al, 2012;SABER et al, 2013) suspended in liquid (DRELISH, 2013) were also reported to both decrease hot press time and improve physical and mechanical properties in wood-composite panels. In this sense, wollastonite nanofiber (as a silicate mineral, CaSiO 3 ) was reported to improve dimensional stability in solid woods (HAGHIGHI et al, 2013), to increase biological durability to fungal rot in solid woods (MARESI et al, 2013), to improve biological resistance against wood-deteriorating fungi in wood-composites , as well as to increase thermal conductivity coefficient in medium-density fiberboard (MDF) .…”

Section: Introductionmentioning

confidence: 99%

Adsorption of Nanowollastonite on Cellulose Surface: Effects on Physical and Mechanical Properties of Medium-Density Fiberboard (Mdf)

Taghiyari

Majidi

Jahangiri

2016

CERNE

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Effects of nanowollastonite (NW) adsorption on cellulose surface were studied on physical and mechanical properties of medium-density fiberboard (MDF) panels; properties were then compared with those of MDF panels without NW-content. The size range of NW was 30-110 nm. The interaction between NW and cellulose was investigated using density functional theory (DFT). Physical and mechanical tests were carried out in accordance with the Iranian National Standard ISIRI 9044 PB Type P2 (compatible with ASTM D1037-99) specifications. Results of DFT simulations showed strong adsorption of NW on cellulose surface. Moreover, mechanical properties demonstrated significant improvement. The improvement was attributed to the strong adsorption of NW on cellulose surface predicted by DFT, adding to the strength and integrity between wood fibers in NW-MDF panels. It was concluded that NW would improve mechanical properties in MDF panels as a wood-composite material, as well as being effective in improving its biological and thermal conductivity. ADSORÇÃO DE NANO WOLLASTONITA NA SUPERFÍCIE DE CELULOSE: EFEITOS NAS PROPRIEDADES FÍSICAS E MECÂNICAS DE PLACAS DE FIBRA DE MADEIRA DE MÉDIA DENSIDADE (MDF)RESUMO: Efeitos da adsorção de nano wollastonite (NW) na superfície de celulose foram estudados nas propriedades físicas e mecânicas de placas de fibra de madeira de média densidade (MDF); as propriedades foram então comparadas com aqueles de painéis de MDF sem NW. A amplitude de tamanho de NW foi 30-110 nm. A interação entre NW e celulose foi investigada usando a teoria do funcional da densidade (DFT). Foram efetuados testes físicos e mecânicos em conformidade com as especificações do Iranian Nacional Standard ISIRI 9044 PB tipo P2 (compatível com ASTM D1037-99). Resultados de simulações de DFT mostraram forte adsorção de NW em superfície de celulose. Além disso, propriedades mecânicas demonstraram melhora significativa. A melhoria foi atribuída à forte adsorção de NW na superfície de celulose prevista pela DFT, agregando força e integridade entre fibras de madeira de painéis de MDF com NW. Concluiu-se que NW melhora propriedades mecânicas em painéis MDF como um material compósito de madeira, além de ser eficaz em melhorar a sua condutividade térmica e biológica.

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Section: Introductionmentioning

confidence: 99%

Adsorption of Nanowollastonite on Cellulose Surface: Effects on Physical and Mechanical Properties of Medium-Density Fiberboard (Mdf)

Taghiyari

Majidi

Jahangiri

2016

CERNE

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“…Nas demais amostras, foi observada presença de cromo e cobalto metálico. O cromo foi identificado segundo o card 060694,e corroborado por Khojier et al [7] Figura 4: Difração de raios X a baixo ângulo da amostra 1 antes do tratamento térmico …”

Section: Estrutura Cristalinaunclassified

Filmes Finos De Cromo Negro Obtidos Por Eletrodeposição

Lana¹,

Nunes²

2017

Anais Do Congresso Anual Da ABM

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ResumoA radiação solar apresenta uma enorme variedade de aplicações de engenharia, dentre elas, a conversão em energia térmica em concentradores solares. Os tubos absorvedores dos concentradores solares podem ser recobertos por cromo negro, com o objetivo de otimizar a absorção energética e a durabilidade. Esse trabalho é parte de um estudo complexo sobre esse tipo de recobrimento. Foram desenvolvidos filmes de cromo negro por eletrodeposição sobre aço inoxidável AISI 304 e tratados termicamente a 600°C por 2 horas. Os filmes foram caracterizados antes e depois do tratamento térmico, utilizando-se microscopia eletrônica de varredura (MEV), espectroscopia de energia dispersiva (EDS) e difração de raios X a baixo ângulo de incidência (GAXRD). Além do cromo, observou-se deposição de cobalto e elementos residuais do banho eletrolítico. O estudo da estrutura cristalina mostrou formação de óxidos após tratamento térmico. Microestruturalmente, foram observados filmes com estrutura lamelar ou nodular. O estudo permitiu sugerir modificações do banho eletrolítico, do substrato e métodos adicionais de caracterização. Palavras-chave: Cromo negro; Deposição eletrolítica; Filmes finos; Difração de raios X a baixo ângulo de incidência. BLACK CHROME THIN FILMS OBTAINED BY ELECTROPLATING AbstractSolar radiation may be used in a wide range of engineering applications, including the conversion into thermal energy in solar power plants. The absorber tubes of solar concentrators can be covered by black chrome, in order to optimize the energetic absorption and durability. This work is part of a complex study about this kind of coating. There were developed thin films of black chrome in 304 stainless steel samples, and annealed at 600°C for 2 hours. The samples were characterized before and after heat treatment using Scanning electron microscope (SEM), Energy dispersive spectrometer (EDS) and glancing angle x-ray diffraction (GAXRD). In addition to chromium, it was observed the deposition of cobalt and residual elements of the electrolytic bath. The study of crystal structure showed the formation of oxide after the heat treatment. Micro-structurally, there were observed films with lamellar or nodular structure. This study allowed the suggestion of changes in the bath composition, substrate and additional characterization methods.

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“…Heat-transferring property of metal nanoparticles (Khojier et al 2012) and mineral nanofibers (Haghighi Poshtiri et al 2013) was reported to improve some properties in solid wood as well as wood-composite materials. However, little study has so far been carried out to practically investigate the effects of different nano-materials in wood-composite panels.…”

Section: Introductionmentioning

confidence: 99%

Effect of silver nanoparticles on hardness in medium-density fiberboard (MDF)

Taghiyari¹,

Norton²

2015

iForest

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© iForest -Biogeosciences and Forestry IntroductionThe harvested wood of fast-growing trees is not usually suitable for the furniture industry; however, they provide a sustainable source for paper and composite-manufacturing industries, and natural regeneration would help the process (Ruprecht et al. 2012, Maresi et al. 2013). Wood-composite panels offer the advantage of a homogeneous structure which may be important for many design purposes (Valenzuela et al. 2012). Due to the low thermal conductivity coefficient of wood (Taghiyari et al. 2013a), some studies have so far been carried out to decrease the maximum pressing time or increase the heat-transferring rate to the core section of the mat (Lehmann et al. 1973, Taghiyari et al. 2013b. Hot press time is dependant on the thickness of the composite mat, press temperature, closing rate, and most importantly, moisture distribution throughout the mat (Doost-Hoseini et al. 2013, Taghiyari et al. 2013b). There is a limit to moisture content of the mat because of two main reasons: (i) increase in the hotpress time; and (ii) occurrence of blows in wood-composite panels. A blow occurs when excess moisture in the board explosively evaporates at temperatures greater than 100 °C, once pressure is released. Furthermore, for urea-formaldehyde (UF) resin, there is a limitation of MC level (Papadopoulos 2007, Stockel et al. 2012. Therefore, rapid transfer of heat to the core section of the mat, and polymerization of resin, has always been a challenge.Many areas of science have used nanotechnology to enhance the effectiveness of materials at nano scales. Heat-transferring property of metal nanoparticles (Khojier et al. 2012) and mineral nanofibers (Haghighi Poshtiri et al. 2013) was reported to improve some properties in solid wood as well as wood-composite materials. However, little study has so far been carried out to practically investigate the effects of different nano-materials in wood-composite panels. The present research project was therefore conducted to study the effects of silver nanoparticles as well as different hot-press times on the hardness of medium-density fiberboards. The relations between the hardness and some physical properties of the panels were investigated as well. Materials and methods Specimen preparationWood fibers were obtained from the Sanaye Choobe Khazar Company (MDF Caspian Khazar, Amol, Iran). The fibers were a mixture of beech, alder, maple, hornbeam, and poplar from forests of the Gillan province (Amol, Iran). The raw materials were free from fungi deterioration. This material was used to prepare boards that were 16 mm thick and had a density of 0.68 g cm -3. A laboratory hot press produced by the Mehrabadi Machinery Mfg. Co. (Tehran, Iran) was used to prepare test specimens. The size of the hot plates was 50 × 50 cm. The total nominal pressure applied by the hot plates was 160 bars at a fixed plate temperature of 150°C. Hot-pressing continued for 6, 8, and 10 minutes. Urea-Formaldehyde resin (UF) was supplied from Pars Chemical Industries ...

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Structural, mechanical and tribological characterization of chromium oxide thin films prepared by post-annealing of Cr thin films

Cited by 37 publications

References 29 publications

Adsorption of Nanowollastonite on Cellulose Surface: Effects on Physical and Mechanical Properties of Medium-Density Fiberboard (Mdf)

Adsorption of Nanowollastonite on Cellulose Surface: Effects on Physical and Mechanical Properties of Medium-Density Fiberboard (Mdf)

Filmes Finos De Cromo Negro Obtidos Por Eletrodeposição

Effect of silver nanoparticles on hardness in medium-density fiberboard (MDF)

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