Cr(N,C) diffusion coating formation on pre-nitrocarburised H13 tool steel

The microstructural processes of Cr(N,C) coating formation by thermoreactive deposition and diffusion (TRD) on pre-nitrocarburised H13 tool steel were studied. Both nitrocarburising and TRD were performed in fluidized bed furnaces at 570 °C. During TRD, chromium was transferred from chromium powder in the fluidized bed, to the nitrocarburised substrates by gas-phase reactions initiated by reaction of HCl gas with the chromium. Addition of 30% H2 to the input inert gas was found to increase the rate of coating formation, although hydrogen reduction resulted in rapid loss of nitrogen to the surface. The reason for the increased rate of coating formation could not be established without further investigation, although several possible explanations have been proposed. It was found that porosity and the formation of an iron nitride ‘cover layer’ during nitrocarburising were the biggest influences on the microstructure of the Cr(N,C) coating. Microstructural characterization of the coatings was performed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and glow discharge optical emission spectroscopy (GDOES).

On rapid vector alignment in permanent magnet brushless motor

A software replacement for the commutation signals of a permanent magnet brushless motor is presented. The feedback observed acceleration loop or equivalently the high-order position polynomial controller allows finding the initial relative orientation between the two magnetic fields of the motors within a fraction of a second. Also, using the proposed method allows a considerable cost saving, since the transducer that is usually used for this purpose can be eliminated. The cost saving is most obvious in the case of linear motors and angle motors with large diameters. The way the problem is posed is an essential part of this work and it is the reason behind the apparent simplicity of the solution. The method has been tested when a relative encoder was used and the motor current was regulated.

Magnet-induced temporary superhydrophobic coatings from one-pot synthesized hydrophobic magnetic nanoparticles.

In this paper, we report on the production of superhydrophobic coatings on various substrates (e.g., glass slide, silicon wafer, aluminum foil, plastic film, nanofiber mat, textile fabrics) using hydrophobic magnetic nanoparticles and a magnet-assembly technique. Fe3O4 magnetic nanoparticles functionalized with a thin layer of fluoroalkyl silica on the surface were synthesized by one-step coprecipitation of Fe2+/Fe3+ under an alkaline condition in the presence of a fluorinated alkyl silane. Under a magnetic field, the magnetic nanoparticles can be easily deposited on any solid substrate to form a thin superhydrophobic coating with water contact angle as high as 172°, and the surface superhydrophobicity showed very little dependence on the substrate type. The particulate coating showed reasonable durability because of strong aggregation effect of nanoparticles, but the coating layer can be removed (e.g., by ultrasonication) to restore the original surface feature of the substrates. By comparison, the thin particle layer deposited under no magnetic field showed much lower hydrophobicity. The main reason for magnet-induced superhydrophobic surfaces is theformation of nano- and microstructured surface features. Such a magnet-induced temporary superhydrophobic coating may have wide applications in electronic, biomedical, and defense-related areas.

Nurses report a healthy culture: Results of the Practice Environment Scale (Australia) in an Australian hospital seeking Magnet recognition

The Magnet Recognition Program requires evidence that the nursing practice environment supports staff to provide optimal care, access professional development opportunities and participate in hospital affairs. This research aimed to assess clinical nurses’ work environment at a leading private hospital in Sydney, Australia using a version of the Practice Environment Scale of the Nursing Work Index modified for the Australian context. Our results were comparable to Magnet hospitals for two subscales and significantly higher than Magnet results for the remaining three subscales and the composite scale. This was especially pleasing in relation to the hospital's preparation for Magnet recognition. Hospitals across Australasia might find administration of the Practice Environment Scale (modified for use in the Australian context) a useful exercise both as a stimulus to preparation and an indicator of readiness for Magnet recognition.

Processing and excellent oxidation resistance of nanocrystalline Fe-Cr alloys

Nanocrystalline and microcrystalline Fe-10Cr alloys were prepared by high energy ball milling followed by compaction and sintering, and then oxidized in air for 52 hours at 400ºC. The oxidation resistance of nanocrystalline Fe-10Cr alloy as determined by measuring the weight gain after regular time intervals was compared with that of the microcrystalline alloy of same chemical composition (also prepared by the same processing route and oxidized under identical conditions). Oxidation resistance of nanocrystalline Fe10Cr alloy was found to be in excess of an order of magnitude superior than that of microcrystalline Fe10Cr alloy. The paper also presents results of secondary ion mass spectrometry of oxidized samples of nanocrystalline and microcrystalline Fe-Cr alloys, evidencing the formation of a more protective oxide scale in the nanocrystalline alloy.

A high performance position sensorless surface permanent magnet synchronous motor drive based on flux angle

A position sensorless Surface Permanent Magnet Synchronous Motor (SPMSM) drive based on flux angle is presented in this paper. The motor equations are written in rotor fixed d-q reference frame. A PID controller is used to process the speed error to generate the reference torque current keeping the magnetizing current fixed. The estimated stator flux using Recurrent Neural Network (RNN) is used to find out the rotor position. The flux angle and the reference current phasor angle are used in vector rotator to generate the reference phase currents. Hysteresis current controller block controls the switching of the 3-phase inverter to apply voltage to the motor stator. Simulation studies on different operating conditions indicate the acceptability of the drive system. The drive system only requires a speed transducer and is free from position sensor requirement. The proposed control scheme is robust under load torque disturbances and motor parameter variations. It is also simple and low cost to implement in a practical environment.