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- PublicationEnhancing the mechanical performance of 3D‐printedbasalt fiber‐reinforced composites using in‐line atmospheric plasma pretreatmentsThe objective of this study is to investigate the use of an air atmospheric plasma jet for the treatment of sized basalt fibres, used in the fabrication of continuous fibre reinforced polypropylene filaments. The plasma treatments were carried out both at a laboratory scale, as well as in-line during the production of fibre reinforced filaments. The latter was carried out at a fibre processing speeds of approx. 15 metres/second, just immediately prior to the polymer coating of the fibre by extrusion. After the air plasma treatment, the water contact angle of the sized basalt fibre decreased from 86° to < 10°. XPS analysis demonstrated that the treatment yielded enhanced levels of oxygen functionality on the fibre surface. After coating with polypropylene, it was observed that there was consistently more homogeneous polymer layer deposited onto the plasma activated fibre, compared with that on the unactivated control fibre. The resulting polymer filament with embedded basalt fibre was used to fabricate mechanical test specimens by 3D printing (fused filament fabrication method). Both three-point bending tests and short beam strength tests were performed. A comparison study was carried out between test specimens fabricated using sized basalt fibre, with and without the plasma pre-treatment. The flexural modulus and maximum shear stress were found to increase by 12% and 13% respectively, for composite's fabricated using the plasma pre-treated basalt fibres. This increased mechanical strength is likely to be due to an increase in interfacial bond strength between the polymer and fibre, with an associated reduction in the level of air incorporation around the basalt filaments as demonstrated using CT analysis.
Scopus© Citations 9 152
- PublicationProcess control of particle deposition systems using acoustic and electrical response signalsThe implementation of statistical quality control methods for monitoring and control of powder abrasion/deposition is of increasing importance in a manufacturing environment. For the wider adoption of both current and new powder coating technologies, quality control systems need to be developed, which are easily installed, non-invasive and work in real time. This study evaluates the use of a dual electro-acoustic and electrostatic surface-charge measurement technique as means of realising real-time process control. Simultaneous changes in the signals were obtained under both powder flow-on and -off conditions and also for edge detection of the substrate. It was discovered that the most important variables which governed changes in the acoustic response signal were due to variations in the deposition pressure and stand-off distance, whilst those for the electrostatic response signal came from changes in particle size and deposition stand-off distance. A phenomenological predictive equation was developed based on a two-level full factorial design with five variables for both response factors. The coefficients of determination, r2, for the models were 93% and 98%, respectively, with respective χ2 probability values of 99% and 99.5%. This enabled the use of specific limits for any variation of variables amongst those tested to be set up, resulting in the apparatus necessary for the development of a sensitive continuous control system. Examining variations in surface roughness with electrostatic signal was observed to show a linear relationship, decreasing at a rate of 0.19 μm per 0.01 eV, as the effective particle size of Al2O3 was increased.
Scopus© Citations 1 379