Hydrophobization of Metal Surfaces

This work describes possibility to create texturized surfaces by their modification using laser equipment with the aim to achieve steady heterogeneous wetting regime. Experimental results regarding the influence of laser radiation variables on wetting angle are given for steel (20Kh13) and aluminum (D16T) surfaces. This was aided by variation of main variables of laser impact, namely: radiation power (from 10 to 20 W), laser beam scanning speed (from 100 to 500 mm/s), pulse frequency (from 20 to 80 kHz). Analysis of the results has revealed that the maximum wetting angles for steel and aluminum surfaces are 147.64° and 150.27°, respectively, they have been obtained upon laser texturizing at the same variables of laser radiation. The influence of laser spot diameter on wetting angle has been determined upon impact on steel (20Kh13) surface. This has been aided by lenses the with focal lengths of 163 and 100 mm, their laser spot diameters are 59 and 25 µm, respectively. It has been revealed that, other conditions being equal, the wetting angles are higher at higher laser spot diameter (59 µm).

Measurement of Cutting Edge Width of a Rotary Cutting Tool by Using a Laser Displacement Sensor

This paper introduces the widthmeasurement of a cutting tool edge by utilizing a laser triangulation displacement sensor. By using the reflected light intensity of the laser displacement sensor, micrometric edge width which is smaller than the diameter of the laser beam spot can be measured. With regard to the quantitative evaluation of the laser spot diameter, a calibration method of the laser spot diameter is achieved by using the pin-gauges. The diameter of the laser spot is obtained by using the pin-gauges, and the relationship between the reflected light intensity and the diameter of the pin-gauges are investigated. The width of the cutting tool edge is measured by the calibrated laser spot diameter, and then the reproducibility is evaluated.

Simulation of Drilling Micro-Hole by a Dual CO2 Laser Beam Irradiated Sticking Plaster

We explore a simulation model of drilling micro-hole in sticking plaster heated with a dual CO2 laser beam. This paper applied numerical simulation of temperature by using finite element analysis software Ansys to study a model of drilling on sticking plaster. A dual CO2 laser spot sizes ranged from 0.15 to 0.2mm radius with axial irradiance power levels of 50-100w. For temperatures above 450°C, sticking plaster would be vaporized. The size of ventilation holes changed with beam power and laser spot diameter. The width of the hole is increases with the increasing laser diameter and with the increasing laser power. These results can guide to laser drilling experiments.

Simulation of Temperature and Stress Field of Titanium Alloys under Laser Cladding

Titanium alloys which exhibit excellent material properties like a high strength to weight ratio and good corrosion resistance have become the important structural materials in the applications of the aerospace. However, it’s quite difficult to repair the damages of the titanium alloy parts such as fatigue crack and erosion resulted from poor working environment using the traditional manufacturing technology while the problem can be easily solved with the help of laser cladding technology. For the excellent quality of the fixed parts, it is extraordinarily significant to obtain the rule of the temperature and thermal stress distribution in the cladding process. To investigate the influencing rule of cladding coating's temperature and stress on laser cladding process parameters, the model of laser cladding based on TC4 titanium alloy is built by the way of finite element method (FEM). This model encompasses the effects of the temperature-dependent thermal conduction and radiation as well as the latent heat of fusion. Different laser processing parameters are chosen to calculate the temperature and stress of cladding layer.The result shows that the temperature of the clad coating is positive correlation with the raise of laser power and the depth of the powder layer, and negative correlation with the raise of scanning speed and the laser spot diameter. In addition, the transient stress of clad coating is augmented with the increase of laser scanning velocity, laser spot diameter and the depth of the clad coating while it’s negative correlation with the raise of laser power. The numerical results provide the theoretical guidance for optimization of the laser cladding parameters on TC4 titanium alloy.

Bending Deformation of Pure Titanium Plate in CO2 Laser Forming

This study deals with behaviour of bending deformation in CO2 laser forming process of titanium. CO2 laser forming technique was applied for a pure titanium plate with thickness of 1 mm to aim the development of new bending process. The experiments of laser forming were carried out with a CO2 laser machine. The bending angle and the temperature of workpiece were examined under the condition of various laser power, feed speed and laser spot diameter. Based on the experimental results, it was found that the bending deformation behaved greatly depending on the laser power and the laser spot diameter. The bending angle increased with an increase in the laser power. The bending direction tended to change from the laser irradiation side to its opposite side when the large laser spot diameter was applied.

Analysis and comparison of semiconductor materials processed at IR vs. UV laser wavelengths for DRAM yield enhancement applications

ABSTRACTThis report demonstrates the effects of IR and UV laser energy on common semiconductor layer stack materials used for DRAM laser fuses. By moving from IR to UV wavelengths it is possible to significantly shrink the laser spot diameter from ∼1.6 μm to 0.8 μm. Effects and concerns for the absorption of UV energy by Si, SiO2, nitrides, and oxynitrides are also presented.