Film surface characterization in cold spray using advanced numerical modeling and simulation techniques
- Authors: Moonga, Kando Hamiyanze , Jen, TienChen
- Date: 2017
- Subjects: Multiple particle impact , Cold spray , Surface roughness
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/241971 , uj:24946 , Citation: Moonga, K.H. & Jen, T.C. 2017. Film surface characterization in cold spray using advanced numerical modeling and simulation techniques.
- Description: Abstract: In cold spray, even when the initial properties are within the critical values for deposition, the multi-impact process is much more complex to ensure a 100% deposition. In inelastic impact, part of the initial kinetic energy of the particles at impact is lost through plastic deformation. After impact and subsequent restitution, unbounded particles will be ejected through rebound forces or material jetting at erosion. Observation of the final kinetic energies achieved in the particles after impact was used as criteria for a rough estimate of the coating process. The surface roughness increased with reduced deposition efficiency. The interface roughness was less affected by this process. Qualitative comparison to experimental results shows some closer correlations with some of the surfaces of experimentally obtained surfaces in cold spray. This could provide some of the answers to the underlying mechanisms in which the cold spray surfaces are generated.
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Influence of coated and uncoated carbide tools on tool wear and surface quality during dry machining of stainless steel 304
- Authors: Sharma, Neeraj , Gupta, Kapil
- Date: 2019
- Subjects: Coating , Friction , Surface roughness
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/407456 , uj:34298 , Citation: Sharma, N., Gupta, K. 2019: Influence of coated and uncoated carbide tools on tool wear and surface quality during dry machining of stainless steel 304.
- Description: Abstract: Machining of difficult-to-machine materials has always been a prime area of investigation for researchers. With regard to that tool wear and surface roughness are some of the most important machinability indicators to evaluate the performance of machining processes. This paper reports a part of investigation conducted on dry turning of SS 304 using uncoated and multilayer coated carbide tools. In this work, the influence of machining parameters on tool wear and surface roughness is studied. The mechanisms of both crater wear and flank wear have been analyzed through scanned electron microscopy and energy dispersive spectroscopy. Moreover, surface roughness (mean roughness depth) profiles have been investigated. Carbide tools coated with TiAlN/TiN alternate layers outperformed uncoated tools with a significant reduction in tool flank wear and mean roughness depth (Rz). The percentage reductions in tool flank wear and Rz were investigated at different levels of input machining parameters. On average approximately 25% reduction in tool wear and 15% reduction in Rz was observed using coated tool than uncoated tool. Furthermore, the tool life has been improved by approximately 200 % after using coated tools. Comparatively less irregular surface while machining with coated tools has been found than uncoated tools. The research is also complemented with a short chip morphology study. The present work recommends the use of multilayer TiAlN/TiN coating on carbide tools for machining of SS 304 under dry conditions.
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Influence of different surface preparations on the capacity of composite steel-concrete beams
- Authors: Rakgate, Sylvester M. , Dundu, Morgan
- Date: 2017
- Subjects: Concrete , Steel plate , Surface roughness
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/248161 , uj:25790 , Citation: Rakgate, S.M. & Dundu, M. 2017. Influence of different surface preparations on the capacity of composite steel-concrete beams.
- Description: Abstract: External bonding of steel plates to structural concrete members has widely gained popularity in recent years, particularly for repairing and strengthening reinforced concrete beams. The success of this bonding technique depends on the effectiveness of the surface preparation of the steel and concrete beams. Studies have shown that most of the beams strengthened using this technique usually fail prematurely by debonding. In this study, concrete beams with different types of surface preparations were investigated, such as no surface preparation (NSP), wire brushing (WB), scabbling (SC) and hand chipping (HC). The quality of the surface preparation established was measured based on the flexural performance of the externally strengthened steel-concrete beams. Eight (8), 250x450x3600 mm reinforced concrete beams were prepared and strengthened with glued steel plates on their soffits. All the specimens were tested under two-point static loading and failure modes were observed. The results showed that beams with rougher surface preparation have a high bond strength as compared to smoother surface preparations. The increase in the average capacity of strengthened beams with the surface prepared by hand-chipping, scabbling, wire brushing was found to be 75.3%, 67.5% and 46.9% respectively, compared to the capacity of the beam strengthened without surface preparation.
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Intelligent optimization of Wire-EDM parameters for surface roughness and material removal rate while machining WC-Co composite
- Authors: Gupta, Kapil
- Date: 2020
- Subjects: Composite , Optimization , Surface roughness
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/481576 , uj:43640 , Citation: Gupta, K. 2020. Intelligent optimization of Wire-EDM parameters for surface roughness and material removal rate while machining WC-Co composite.
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Surface engineering of titanium for biomedical applications by anodizing
- Authors: Manjaiah, M. , Laubscher, Rudolph F.
- Date: 2016
- Subjects: Titanium grade 4 , Anodization , Surface roughness
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/123422 , uj:20789 , Citation: Manjaiah, M & Laubscher, R.F. 2016. Surface engineering of titanium for biomedical applications by anodizing.
- Description: Abstract: Competitive manufacturing implies fit for purpose and efficient manufacturing practices. Dental implants are biomedical parts that are manufactured from either Grade 4 or 5 Titanium alloy. In certain situations it may be beneficial for patient satisfaction purposes and for product identification marking to change the appearance (colour and reflectance) of the implant. In the present study, a TiO2 based coating is applied on commercially pure titanium (Grade 4) alloy substrates by the anodizing process. The objective of this study was to engineer the aesthetic appearance of the dental implants while monitoring its effect on aspects as regards to biocompatibility and function. Chromaticity (colour and hue) and reflectance are investigated as a function of the anodizing process parameters (electrolyte voltage, current and electrolyte). Grade 4 titanium was anodized in diluted sulphuric acid electrolyte at various voltages. The reflectance of the anodized specimens was measured with a spectrophotometer. Surface roughness, oxide film thickness and chemical composition of the oxide phase were measured. By varying the electrolyte voltage between 5 V to 40 V different colour ranges were produced. It can be concluded that the surface colour of anodized titanium is dependent on the oxide layer thickness and therefore the applied voltage. Conventional surface roughness did not change and was similar to the virgin material. Elevated voltages resulted in a more crystalline oxide layer. The aesthetic appearance of titanium implants may be improved.
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The perception of gloss : a comparison of three methods for studying intentionally polished bone tools
- Authors: Bradfield, Justin
- Date: 2020
- Subjects: Polished bone , Atomic force microscopy , Surface roughness
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/426635 , uj:36602 , Bradfield, J. 2020: The perception of gloss : a comparison of three methods for studying intentionally polished bone tools. DOI: https://doi.org/10.1016/j.jasrep.2020.102425
- Description: Abstract: Polished bone and stone tools are well known from many archaeological contexts. In use-wear studies, polish is usually characterised by the degree of surface roughness, or more subjectively by its visual appearance. Visual appearances, however, may be deceptive, and the scale of analysis of traditional surface roughness studies is often too fine to consider the overall visual effect of a polished surface. Here I consider three techniques for characterising modified bone surfaces and assess the correlation between surface roughness and gloss. My results show that softer contact materials generally produce higher gloss values than harder materials, but within these two broad categories results are more complex. Based on these experimental results a trial assessment is presented of archaeological bone tools from assorted Holocene sites. The ability to perceive and appreciate polished surfaces is linked to developments in the superior temporal sulcus region of the human brain, which is the same region in which our ability to perceive shapes and colour developed. Deliberately polished bone tools from Pleistocene contexts therefore have the potential to provide insights into cognitive developments in our species. The specular reflectance or gloss of a polished surface provides a quantifiable and repeatable measure, more suitable than surface roughness analysis, for characterising deliberate polish, although a combined approach is advocated.
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