Wettability, Microhardness, Wear and Corrosion Resistance of Ni–Co–P–BN(h)–Al2O3 Binary Nanocomposite Coatings Surface with Varying Long-Pulse Laser Parameters

In this study, Ni–Co–P–BN(h)–Al2O3 binary nanocomposite coatings were fabricated on steel C1045 substrates by jet electrodeposition. The samples were then processed using self-made laser processing equipment to investigate the influence of long-pulse laser processing parameters variation on samples’ surface morphology, roughness and wettability. Additionally, the properties of samples before and after laser processing were analyzed and characterized. The results showed that the surface morphologies, surface roughness and wettability of samples were affected by laser output power, pulse width and spot-to-spot distance variation. A convex dome was formed on the samples’ surface at a low laser output power and a suitable pulse width, while a dimple was formed on the samples’ surface at a high laser output power. The surface roughness and water contact angle of samples increased with the rise in laser output power or pulse width. The water contact angle decreased with the rise in the spot-to-spot distance, and the water contact angle reached a maximum value of 139.8° with a laser output power of 50 W, a pulse width of 100 µs and a spot-to-spot distance of 150 µm. The samples after laser processing exhibited a higher wettability, microhardness and wear resistance compared to those of the normal samples. The microhardness of the heat-affected zone reached a maximum value of 812.1 HV0.1, and the wear scar width of the samples reached a minimum value of 360.5 µm. However, after laser processing, the samples’ seawater corrosion resistance decreased slightly.

Selective Laser Melting of Magnesium

Magnesium-based materials find their use mainly in manufacturing light-weight constructions in motor-car, airspace industries, and biomedicine due to the low density. This paper provides an overview of introducing magnesium into SLM technology and describes searching experiments to prepare samples of magnesium powder МPF-4 (Russian State Standard 6001-79) conducted in the Laboratory of Yurga Institute of Technology. The study has determined appropriate parameters to synthesize a compact structure: laser output power 100 W, laser beam movement velocity 200 mm/s, scanning pitch 0.1 mm, modulation frequency of laser irradiation m = 2500 Hz, linear energy density Е=5 J/mm2, the process is to be carried out in argon shielding medium.

Simulation and analysis of the time evolution of laser power and temperature in static pulsed XPALs

A theoretical model is established to describe the thermal dynamics and laser kinetics in a static pulsed exciplex pumped Cs–Ar laser (XPAL). The temporal behaviors of both the laser output power and temperature rise in XPALs with a long-time pulse and multi-pulse operation modes are calculated and analyzed. In the case of long-time pulse pumping, the results show that the initial laser power increases with a rise in the initial operating temperature, but the laser power decreases quickly due to heat accumulation. In the case of multi-pulse operation, simulation results show that the optimal laser output power can be obtained by appropriately increasing the initial temperature and reducing the thermal relaxation time.

POWER SCALING IN CONTINUOUS-WAVE YB:YAG MICROCHIP LASER FOR MEASURING APPLICATIONS

Characteristics optimization of lasers used in different measuring systems is of great interest up to now. Diode-pumped microchip lasers is one of the most perspective ways for development of solid-state light sources with minimal size and weight together with low energy power consumption. Increasing of output power with good beam quality is rather difficult task for such type of lasers due to thermal effects in the gain crystal under high pump power.The investigation results of continuous-wave longitudinally diode-pumped Yb:YAG microchip laser are presented. In the presented laser radiation from multiple pump laser diodes were focused into the separate zone in one gain crystal that provides simultaneous generation of multiple laser beams. The energy and spatial laser beam characteristics were investigated.Influence of neighboring pumped regions on energy and spatial laser beams parameters both for separate and for sum laser output was observed. The dependences of laser output power from distance between neighboring pumped regions and their number were determined. Decreasing of laser output power was demonstrated with corresponding distance shortening between pumped regions and increasing their quantity with simultaneous improvement of laser beam quality.Demonstrated mutual influence of neighboring pumped regions in the longitudinally diode pumped Yb:YAG microchip laser allow as to generate diffraction limited Gaussian beam with 2W of continuous-wave output power that 30 % higher than in case of one pumped zone.

Temperature Sensor Using a Multiwavelength Erbium-Doped Fiber Ring Laser

A novel temperature sensor is presented based on a multiwavelength erbium-doped fiber ring laser. The laser is comprised of fiber Bragg grating reflectors as the oscillation wavelength selecting filters. The performance of the temperature sensor in terms of both wavelength and laser output power was investigated, as well as the application of this system for remote temperature measurements.