Surface Quality Of Composites Research Articles

Effect of dry abrasion treatments on composite surface quality and bonded joints shear strength

In order to enhance the adhesion properties of composites for further use in structural bonding applications, the effect of different surface treatments on flax/epoxy composite surface topography, surface arithmetic mean height (Sa), surface free energy ( γ s ) and composite to composite bonded joints shear strength (τ) was studied in this research. The main goal of this work was to evaluate the efficiency of abrasion surface treatments, such as sandblasting and sanding in enhancing composites’ adhesion quality compared to traditional mechanical surface treatments such as peel ply. Surface topography was evaluated using an optical microscope. Surface arithmetic mean height (Sa) was estimated via a mechanical surfscan. Surface free energy ( γ s ) was determined using the contact angle method along with the two-component Owens-Wendt model. Composite bonded joints shear strength was evaluated using the single lap shear joint test (SLJ). Trials revealed that specimens treated with sandblasting presented the highest composite bonded joints shear strength (τ). These specimens were characterized by a non-homogeneous surface topography, the highest surface arithmetic mean height (Sa) along with the highest surface free energy ( γ s ) and surface free energy dispersive component ( γ s d ).Unlike peel ply, sandblasting and sanding caused fiber exposure at the surface level. Sand granulometry used for sandblasting had an effect on the composite surface quality and its bonded joints shear strength. Linear regression revealed that composite bonded joints shear strength increases with the increase of the surface free energy dispersive component ( γ s d ). Abrasion treatments such as sandblasting significantly enhanced the adhesion properties of the composite compared to peel ply. Yet it did cause some side effects such as flax fiber damage and sand residue. These side effects could be reduced by opting for less harsh abrasive sand and more sophisticated cleaning processes.

Experimental study on mechanical drilling of carbon/epoxy composite-Ti6Al4V stacks

ABSTRACTThis paper concerns the experimental studies on the drilling process of multilayer carbon/epoxy composite-Ti6Al4V stacks and their individual material layers using tungsten carbide drills. The significance of the current work aims to reveal the impact of tool wear on the drilling process for CFRP/Ti6Al4V, CFRP and Ti6Al4V. Four groups of machining tests including drilling individual CFRP, individual Ti6Al4V, multilayer CFRP/Ti6Al4V stacks with and without a cooling treatment were conducted. Drilling forces, cutting temperatures and hole quality attributes were experimentally investigated in terms of the drill wear extents. The mechanism controlling the tool wear effect on the drilling machinability of CFRP/Ti6Al4V was revealed, providing several implications for the industrial manufacturers. The results highlight the significant impact of the titanium chip ejection on the composite surface quality and the necessity of a rigorous tool wear control to guarantee the damage-free drilling of CFRP/Ti6Al4V stacks.

Experimental Study on C<sub>sf</sub>/AZ91D Composite Using Extrusion Following Vacuum Infiltration Method

10vol. % Csf/AZ91D composites were fabricated by extrusion following vacuum infiltration process with self-developed experimental device and measuring system. The relationships of load vs displacement during process and surface quality of composites at various extrusion temperatures were investigated. SEM microscope was used to observe the microstructure of fabricated composites. The experimental results showed that the extrusion process can be divided into three deformation stages. The extrusion temperature had a great influence on the maximum extrusion load. Based on proper infiltration parameters, a extruded bar with good surface quality was obtained at extrusion temperature of 420°C.