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Article
Publication date: 28 October 2019

Xiaoqing Ni, Liang Zhang, Wenheng Wu, Dexiang Zhu, Decheng Kong, Chaofang Dong and Guoliang Zhu

Laser melting deposition (LMD) is an advanced additive manufacturing (AM) technology without powder waste, and nickel-based alloys with different Nb contents were created one-time…

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Abstract

Purpose

Laser melting deposition (LMD) is an advanced additive manufacturing (AM) technology without powder waste, and nickel-based alloys with different Nb contents were created one-time by adjusting the ratio of mixed powders via a dual-feed system. Here, the authors provide a systematic report on the effects of the Nb content on the microstructure, Laves phase segregation and mechanical properties of as-received LMD nickel-based alloys. The effects of the Nb content on the microstructure, precipitation evolution and mechanical properties of the subsequent heat-treated LMD samples are also discussed in this paper.

Design/methodology/approach

Thus, the present research aims to obtain a better understanding of the effect of Nb content on the microstructural and mechanical properties of the as-received LMD Inconel 718 alloys through high-throughput sample fabrication. The microstructures were characterized by scanning electron microscopy and energy-dispersive spectroscopy, electron back-scattered diffraction and transmission electron microscopy methods. The mechanical properties were obtained from compressive tests and nano-indentation tests. Electrochemical tests, including electrochemical impedance spectroscopy and potentiodynamic polarizations, were carried out to evaluate the durability of the Inconel 718 alloys. Results can provide a factual basis for future applications of the functionally graded by AM technology.

Findings

The grain size of the as-received LMD Inconel 718 alloys decreased with the Nb content. The Laves phase distribution at the macro level was relatively uniform and the Laves phase exhibited a 1.5-fold nano-hardness compared with the matrix. The strength improvement for the as-received LMD Inconel 718 alloys with Nb content was attributed to grain refinement and enhancement of the Laves phase in terms of both hardness and content. Meanwhile, the corrosion resistance increased with the increase of the Nb content, especially for the pitting potential, which was attributed to the optimization of carbide precipitates due to the strong affinity between niobium and carbon.

Originality/value

The results provide a factual basis for the Nb content effect in LMD nickel-based alloys, and this method can greatly promote the development of new materials. The authors believe that this study makes a significant contribution to the literature and is suitable for publication.

Details

Anti-Corrosion Methods and Materials, vol. 67 no. 1
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 3 June 2019

Sandriane Pizato, Raquel Costa Chevalier, Marcela Félix Dos Santos, Tailine Saturnino Da Costa, Rosalinda Arévalo Pinedo and William Renzo Cortez Vega

The purpose of this paper is to evaluate the shelf-life of minimally processed pineapple when subjected to the use of different edible coatings.

454

Abstract

Purpose

The purpose of this paper is to evaluate the shelf-life of minimally processed pineapple when subjected to the use of different edible coatings.

Design/methodology/approach

The pineapples were peeled and cut into cubes. The gums were prepared by dissolving them in distilled water and then heated to total dissolution. After calcium chloride, citric acid and ascorbic acid and glycerol were added in the solutions. The pieces of pineapple were completely submerged in the respective solutions and then drained. Four treatments were obtained, namely: T1 – control treatment (pineapple without coating); T2 – pectin; T3 – tara; T4 – xanthan. The cubes were stored in PET by 12 days at 4±1°C. Analyzes were carried out of mass loss, pH, titratable acidity, soluble solids, microbiological and sensory analysis.

Findings

It was possible to observe that the use of evaluated coatings was efficient to maintain the conservation of minimally processed pineapple in all analyzes, when compared with the control sample. The treatment with tara gum showed the best results to those obtained by the other studied gums.

Practical implications

The study may help small-scale establishments to increase the shelf-life of minimally processed pineapple.

Originality/value

Tara gum reduced the mass loss, delayed the microbial growth and maintained the sensorial quality of minimally processed pineapples for a longer time.

Details

British Food Journal, vol. 121 no. 7
Type: Research Article
ISSN: 0007-070X

Keywords

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