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Sapphire is a widely used hard transparent material for optics and protective windows, and a superhydrophobic coating on sapphire can prevent contamination by self-cleaning. However, the coating can be easily degraded according to time and heat. In this research, transparent superhydrophobic sapphire surfaces were fabricated via laser surface ablation, without coating, for good stability and heat resistance. The laser ablated surface showed hydrophilic initially, but the wettability transition to superhydrophobic was achieved after an additional simple heat treatment. Contact angle and transmittance were measured to confirm the superhydrophobicity and transparency, and surface analysis was performed to explain the wetting mechanism. [ABSTRACT FROM AUTHOR]

A basic scheme of an ablation pulsed plasma thruster with rail geometry and a side feed of the propellant bar is considered. For such geometry, a theoretical description of the initial stage of the vacuum discharge, which would serve to explain the experimental results, does not exist. It was demonstrated experimentally that the configuration of the discharge channel depends essentially on the initial stage of discharge. A model of the motion of charged particles in the inhomogeneous electric and magnetic fields was developed. Due to the low plasma density at the initial stage of discharge, the model of the charged particles motion in electric and magnetic fields is described well by differential equations. [ABSTRACT FROM AUTHOR]

This contribution gives the first results of an ongoing research aiming at developing a new surface treatment technique usinga supercritical nitrogen jet, named Jazolthop, for surface modification. As nitrogen is naturally recycled within air, this new process has a high potential for surface treatment without any chemical, physical or sewage effluents. This contribution shows that, pending on the operating condition, the technique can be used (i) under a stripping or ablation mode as well as, in a “less conventional” approach, (ii) for surface hardening. Illustration of the ablation mode is given for a Ti-6Al-4 V alloy treated under static conditions using an intrusive jet. After 2 min of treatment, a thickness of 200 μm was removed from the surface by successive stripping out of micro-chips. Illustration of the hardening mode is given through the analysis of stainless steels treated under the cryogenic jet at a moving torch velocity of 5 mm/min. The jet conditions were selected to be less intrusive and trigger the martensitic transformation without creating surface flaws of micro-cavities. In this case, the hardness of the steels was more than doubled after the passage of the cryogenic jet. [ABSTRACT FROM AUTHOR]

Abstract: The radiative performance of Z-pinches created by the imploding wire array loads is defined by the ablation and implosion dynamics of these loads. Both these processes can be effectively modeled by the Wire Ablation Dynamics Model (WADM), which extends the formalism exploited earlier for the cylindrical wire arrays to the loads of arbitrary geometries. The WADM calculates the ablation rates for each array wire and provides the important dynamic parameters, such as the specific mass and velocity of the imploding plasma, which can be used to estimate the shapes of the x-ray pre-pulse and, partially, the main x-ray burst. The applications of the WADM also extend to combined material wire array loads. The ablation and implosion dynamics of novel Prism Planar Wire Array (PPWA) and combined material (Mo/Al/Mo) Triple Planar Wire Array (TPWA) loads are discussed in detail. The combined WADM and radiation MHD simulation is applied to model the radiative performance of the precursor plasma column, created by the imploding stainless steel compact cylindrical wire array. As the radiation effects intensify with the mass accumulation at the array center, the simulation reveals the transformation of quasi-uniform precursor column into a heterogeneous plasma structure with strong density and temperature gradients. We find that radiative performance of the precursor plasma is greatly affected by the load geometry as well as by the wire material. [Copyright &y& Elsevier]

The paper presents a series of researches regarding the vaporization of the component elements of the metallic bath and slag during refining in LD converter. Also, the main factors which influence the vaporization process during steel making in LD converter are studied: the converter atmosphere; the carbon content of the metallic bath; the speed of the oxygen jet; the temperature of the metallic bath; the blowing diagram. Based on these researches we sought to obtain a technology of steel making in LD converter so that the percentage of losses by vaporization is minim. [ABSTRACT FROM AUTHOR]

Provides tips on possible problems that may be encountered in steam trap operation. Types of steam trap; Common problems of steam traps; Remedy when the valve set assemble is worn out.