Laser texturing of soda lime glass surface for hydrophobic surface in wenzel state

Glass surfaces tend to be hydrophilic when exposed to water resulting in a low water contact angle and high adhesion. Fabrication on a glass surface with low water adhesion can minimize the droplet’s adhesion conduct self-cleaning, and improve the cleanliness of the glass surface. This paper presents surface texturing of the soda-lime glass surface by laser processing three different patterns to improve water contact angle with low water adhesion on the modified glass surface. A design experiment method was developed to determine the effects of laser parameters on the glass surfaces. The laser parameters used are laser power between 0.45 and 1.05W and scanning speeds of 210, 420, and 600 mm/min. The effects of laser parameters on surface morphology, water contact angle measurement, and average surface roughness, Ra were investigated. The characterization was conducted for surface morphology, two-dimensional surface roughness profile, and water contact angle. The results show that the highest water contact angle obtained after laser texturing is up to 125.29° compared to the as-received surface with a contact angle of 32.35°. The highest water contact angle resulted from 420 mm/min scanning speed and 0.45 W of laser power, responding to the surface with a minimum range of Rax and Ray of 0.96 and 1.5 pm. These findings are significant for designing surface modification of self-cleaning glass surface applications like the automotive windscreens, and window panels for high-rise buildings

Thermomechanical modelling of laser surface glazing for H13 tool steel

A two-dimensional thermomechanical finite element (FE) model of laser surface glazing (LSG) has been developed for H13 tool steel. The direct coupling technique of ANSYS 17.2 (APDL) has been utilised to solve the transient thermomechanical process. A H13 tool steel cylindrical cross-section has been modelled for laser power 200 W and 300 W at constant 0.2 mm beam width and 0.15 ms residence time. The model can predict temperature distribution, stress–strain increments in elastic and plastic region with time and space. The crack formation tendency also can be assumed by analysing the von Mises stress in the heat-concentrated zone. Isotropic and kinematic hardening models have been applied separately to predict the after-yield phenomena. At 200 W laser power, the peak surface temperature achieved is 1520 K which is below the melting point (1727 K) of H13 tool steel. For laser power 300 W, the peak surface temperature is 2523 K. Tensile residual stresses on surface have been found after cooling, which are in agreement with literature. Isotropic model shows higher residual stress that increases with laser power. Conversely, kinematic model gives lower residual stress which decreases with laser power. Therefore, both plasticity models could work in LSG for H13 tool steel

Porosity study and effects on mechanical properties of discontinuous reinforced metal matrix composite (DRMMC)

The effects of porosity on mechanical properties of cast discontinuous reinforced meta] matrix composite (DRMMC) were investigated. Hence, a casting rig was fabricated to produce DRMMCs via conventional and modified stir casting method . The modified stir casting method performed pre-heating of reinforcement particles during matrix alloy melting. Silicon carbide particle reinforced aluminium alloy composites were produced with three different stirring speeds: 100, 200 and 500rpm. Cast DRMMCs were evaluated in as-cast condition for microstructure analysis, porosity and density measurement and mechanical testing. The mechanical properties of cast DRMMC were determined from tensile and fatigue tests conducted at room temperature. Tensile tests were referred to ASTM B557 standard while the axial fatigue test (ASTM E466) was conducted at stress ratio (R) of -1. A finite element method (FEM) analysis was carried out using Solidworks 2003 software. It was found that the major causes of porosity occurrence in cast DRMMC were clustered silicon carbide particles, gas entrapment and solidification shrinkage. From porosity measurement, conventionally stir cast DRMMCs contained higher porosity compared to the modified stir cast DRMMCs. The least content of porosity evaluated is at 0.09% in modified stir cast DRMMC, while the highest is at 12.45% in conventionally stir cast DRMMC. Fatigue strength (at 1 x 107 cycles) of cast DRMMCs at 5, 10, and 15% reinforcing SiC particle were 129.7, 141.5 and 157.3 MPa respectively. Based on the FEM analysis, porosity in conventionally stir cast DRMMC promotes higher von Mises stress as much as 40.2 MPa compared to 12.6 MPa in modified stir cast DRMMC. The porosity contents increased with increasing silicon carbide particles. Higher stirring speed tended to entrap more gas during mixing, whereas a lower stirring speed was ineffective to disperse SiC particles and results in clustering. Increasing porosity content in cast DRMMC had decreased the density and tensile properties ofDRMMC as depicted by the FEM analysis. Though, fatigue strength increased as a result of existing constraints in form of porosity

Proposity study and effects on mechanical properties of discontinuous reinforced metal matrix composite (DRMMC)

The effects of porosity on mechanical properties of cast discontinuous reinforced meta] matrix composite (DRMMC) were investigated. Hence, a casting rig was fabricated to produce DRMMCs via conventional and modified stir casting method . The modified stir casting method performed pre-heating of reinforcement particles during matrix alloy melting. Silicon carbide particle reinforced aluminium alloy composites were produced with three different stirring speeds: 100, 200 and 500rpm. Cast DRMMCs were evaluated in as-cast condition for microstructure analysis, porosity and density measurement and mechanical testing. The mechanical properties of cast DRMMC were determined from tensile and fatigue tests conducted at room temperature. Tensile tests were referred to ASTM B557 standard while the axial fatigue test (ASTM E466) was conducted at stress ratio (R) of -1. A finite element method (FEM) analysis was carried out using Solidworks 2003 software. It was found that the major causes of porosity occurrence in cast DRMMC were clustered silicon carbide particles, gas entrapment and solidification shrinkage. From porosity measurement, conventionally stir cast DRMMCs contained higher porosity compared to the modified stir cast DRMMCs. The least content of porosity evaluated is at 0.09% in modified stir cast DRMMC, while the highest is at 12.45% in conventionally stir cast DRMMC. Fatigue strength (at 1 x 107 cycles) of cast DRMMCs at 5, 10, and 15% reinforcing SiC particle were 129.7, 141.5 and 157.3 MPa respectively. Based on the FEM analysis, porosity in conventionally stir cast DRMMC promotes higher von Mises stress as much as 40.2 MPa compared to 12.6 MPa in modified stir cast DRMMC. The porosity contents increased with increasing silicon carbide particles. Higher stirring speed tended to entrap more gas during mixing, whereas a lower stirring speed was ineffective to disperse SiC particles and results in clustering. Increasing porosity content in cast DRMMC had decreased the density and tensile properties ofDRMMC as depicted by the FEM analysis. Though, fatigue strength increased as a result of existing constraints in form of porosit

Micro-Bulges Investigation on Laser Modified Tool Steel Surface

This paper presents micro-bulges investigation on laser modified tool steel. The aim of this study is to understand the effect of laser irradiance and interaction time on surface morphology configuration. An Nd:YAG laser system with TEM00 pulse processing mode was used to modify the samples. Metallographic study shows samples were analyzed for focal position effect on melted pool size, angle of peaks geometry and laser modified layer depth. Surface morphology were analyzed for surface roughness. Laser modified layer shows depth ranged between 42.22 and 420.12 μm. Angle of peak bulge was found to be increase with increasing peak power. The maximum roughness, Ra, achieved in modified H13 was 21.10 μm. These findings are significant to enhance surface properties of laser modified steel and cast iron for dies and high wear resistance applications

Fiber Laser Welding of Dissimilar 2205/304 Stainless Steel Plates

In this study, an attempt on pulsed-fiber laser welding on an austenitic-duplex stainless steel butt joint configuration was investigated. The influence of various welding parameters, such as beam diameter, peak power, pulse repetition rate, and pulse width on the weld beads geometry was studied by checking the width and depth of the welds after each round of welding parameters combination. The weld bead dimensions and microstructural progression of the weld joints were observed microscopically. Finally, the full penetration specimens were subjected to tensile tests, which were coupled with the analysis of the fracture surfaces. From the results, combination of the selected weld parameters resulted in robust weldments with similar features to those of duplex and austenitic weld metals. The weld depth and width were found to increase proportionally to the laser power. Furthermore, the weld bead geometry was found to be positively affected by the pulse width. Microstructural studies revealed the presence of dendritic and fine grain structures within the weld zone at low peak power, while ferritic microstructures were found on the sides of the weld metal near the SS 304 and austenitic-ferritic microstructure beside the duplex 2205 boundary. Regarding the micro-hardness tests, there was an improvement when compared to the hardness of duplex and austenitic stainless steels base metals. Additionally, the tensile strength of the fiber laser welded joints was found to be higher when compared to the tensile strength of the base metals (duplex and austenitic) in all of the joints