Effect of Process Variables on the Formation of Streak Defects on Anodized Aluminum Extrusions: An Overview

Zhu, Hanliang; Couper, Malcolm J.; Dahle, A. K.

doi:10.1515/htmp-2012-0024

Cited by 8 publications

(5 citation statements)

References 7 publications

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“…The grain structure of aluminium oxide coatings grown on extruded alloy F (a 6xxx series alloy) had a similar structure to the alloys imaged by Zhu et al (2012) and Ma et al (2013), verifying the success of the sample preparation method used here for plan view SEM photomicrographs. The aluminium oxide coating grown on alloy H (5754) also exhibited a similar surface morphology (i.e.…”

Section: Plan View Sample Preparationsupporting

confidence: 61%

“…groove shaped imperfections along grain boundary regions formed due to preferential attack of grain boundaries) and etching pits. Etching pits are surface scallops or cavities formed as a consequence of different etching behaviours between intermetallic particles or inclusions and the aluminium matrix (Zhu et al, 2012;Ma et al, 2013). These features were significantly different for a particular aluminium alloy as depicted in Fig.3.…”

Section: Imagingmentioning

confidence: 99%

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Sample preparation of anodised aluminium oxide coatings for scanning electron microscopy

Long

Borissova

Wilson³

et al. 2017

Micron

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Sample preparation of anodised aluminium oxide coatings for scanning electron microscopy.Micron http://dx.doi.org/10.1016/j.micron. 2017.06.010 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Research Highlights Anodised aluminium oxide coating samples were prepared for SEM examination. Three preparation methods were trialled to assess coating thickness and structure. Cryogenic fracturing was found to be destructive to samples. Mechanical fracturing provided relatively accurate coating thickness measurements. Coating structure could only be evaluated from mechanically fractured samples. 2 AbstractCharacterisation of anodic aluminium oxide coatings and measurement of their thickness using microscopic techniques is valuable for analysing the effectiveness of the prior anodising process. Three different methods for preparing samples to view the coating cross-section (mechanical fracturing, cryogenic fracturing and metallography) were trialled and assessed for speed of implementation, simplicity and achievable measurement accuracy. Cryogenic fracturing was found to be destructive to samples. Mechanical fracturing yielded relatively accurate coating thickness measurements and coating structural information. Metallography provided the most accurate coating thickness measurement at the expense of coating structural information.

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Section: Plan View Sample Preparationsupporting

confidence: 61%

Section: Imagingmentioning

confidence: 99%

Sample preparation of anodised aluminium oxide coatings for scanning electron microscopy

Long

Borissova

Wilson³

et al. 2017

Micron

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“…The influence of repeated nitriding on the surface structure of matrices and new methods of nitriding were also investigated in the works of Borowski et al [ 3 , 4 ]. The effect of overheating of the matrix and the extrusion ingot on the formation of streak defects was investigated by Zhu et al [ 5 ], who considered influencing factors involved in various processing steps such as billet quality, extrusion process, die design and etching process. Kugler et al [ 6 ] pointed out that the quality of the matrix-bearing surface as well as its tribology and geometric conditions determine the quality of the product surface.…”

Section: Introductionmentioning

confidence: 99%

Influence of Operating Temperature on the Service Life of Aluminum Extrusion Dies

Hubicki¹,

Richert

Łebkowski

2022

Materials

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The article investigates the effect of temperature and annealing time on the surface quality of WNLV nitrided steel used for the production of dies for extrusion of aluminum alloys. Eight annealing variants were tested, differing in the total annealing time at temperatures of 460 °C and 590 °C. The results show the effect of the annealing time on the width of the diffusion layer, which increased with the increasing length of the annealing time. The hardness decreased as the annealing time increased. It was found that annealing of the steel causes its oxidation. The oxide layer formed consisted of two layers, more specifically, an Fe2O3 oxide layer and a lower Fe3O4 oxide layer adhering to the steel surface. The surface of sections pressed on oxidized matrices was tested. The roughness of the surface of the oxide layers was also tested. The research revealed that an increase in the surface roughness of the oxides deposited on the matrices causes an increase in the roughness of the extruded sections. These results can potentially be used to improve the efficiency of the extrusion process and the quality of the extruded sections.

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“…However, with recent increase in the use of recycled Aluminium alloys for environmental sustainability and cost effectiveness, the quality control of anodised surfaces is increasingly becoming difficult. This is due to the higher degree of heterogeneity in recycled Al alloys that contain a higher number of intermetallic or constituent phase particles, which leads to higher heterogeneity in the electrochemical nature thus altering the anodising behaviour and the decorative finish of the anodised surface [9,[49][50][51][52][53][54][55][56][57]. Various authors have emphasized on the importance of the alloy composition, morphology and microstructure of the Al surface and its effect on the anodising behaviour and optical appearance [58] [59].…”

Section: Introductionmentioning

confidence: 99%

High frequency pulse anodising of aluminium: Anodising kinetics and optical appearance

Jensen

Gudla

Kongstad

et al. 2019

Surface and Coatings Technology

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High frequency pulsed anodising of pure aluminium was investigated with an aim to understand the effect of the anodising parameters on the growth kinetics of the anodic layer and optical appearance of the anodised surface. Anodising was performed in sulphuric acid, and the effect of the pulse duty cycle, applied potential offset, and pulse frequency was investigated. Optical properties of the anodised surfaces are improved upon lowering the anodising potential and by increasing the frequency of the applied potential pulses. Temperature evolution of the samples during anodising was investigated by employing a special flat cell setup equipped with a thermocouple close to the sample. The effect of high frequency pulsing of the anodising potential on the anodising kinetics is presented, which is related to the temperature evolution and dielectric losses, and the effect is compared to the traditional DC anodising process. From the observations, it is postulated that the dominant factor responsible for the improved growth kinetics during high frequency pulsed anodising might not be dielectric losses instead a thickness reduction in the Gouy-Chapman/Helmholtz layers.

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Effect of Process Variables on the Formation of Streak Defects on Anodized Aluminum Extrusions: An Overview

Cited by 8 publications

References 7 publications

Sample preparation of anodised aluminium oxide coatings for scanning electron microscopy

Sample preparation of anodised aluminium oxide coatings for scanning electron microscopy

Influence of Operating Temperature on the Service Life of Aluminum Extrusion Dies

High frequency pulse anodising of aluminium: Anodising kinetics and optical appearance

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