Determination of Relation between Elastic Constant and Si ntered Temperature in WC-Ni Composites
In this study we have investigated relation between elasti c constant and sintered temperature in tungsten carbide- nickel composite samples. Determination of elastic properties of materials is based on the transverse and longitudinal wave’s velocities via ultrasonic methods. In this study ultrasonic velocity measurements were measured in the WC-Ni composites. These samples are formed by powder metallurgy and electroless plating. Samples were sintered at temperat ures of 1000 °C, 1100 °C, 1200 °C and 1300 °C with Ar gas atmosphere in tube furnace. In the measuring ultrasonic longitudinal velocity 2 and 5 MHz transducers, ultrasonic transverse velocity 1 and 5MHz transducers have been used. Young Modulus (E) has been calculated by using longitudinal and transverse velocity. A fter we calculated elastic constant, we have investigated relation between sinter ed temperature and elastic constant of samples. A linear relation between sinter ed temperature and elastic constant in samples is observed.
Electroless nickel-boron coatings on metal carbides
Abstract Electroless deposition is a very simple process which can be used to obtain amorphous metallic coatings of uniform thickness on metallic or non-metallic substrates. In this work, nickel-boron coatings were deposited by electroless plating on WC and VC powders and sintered substrates. Two electrolyte solutions for the deposition of Ni-B coatings were developed: an alkaline and an acidic bath, both based on nickel chloride. Coating characterization was carried out by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Auger electron spectroscopy (AES) and X-ray diffraction (XRD). Both electrolytes produced continuous firms of uniform thickness on sintered carbide substrates; the acidic bath showed a higher deposition rate. Furthermore on the carbide powders it produced crack-free Ni-B continuous coatings. Ni was detected by EDS and the coating purity was confirmed by AES. XRD proved that amorphous coatings were obtained in all cases.
Preliminary Investigation on Laser Ultrasonic NDE of Nano-meter Materials
Some experimental results about laser ultrasonic NDE of nano-meter materials of silver and copper (hereafter mnAg and nmCu) are obtained. A pulsed laser is used as the ultrasonic source, and a capacitive transducer as the receiver. The phenomenon related to the particle size effect and the interface effect between particles of nano-mater material is observed. The response signal resulting from artificial interface layer in nmCu is clearly seen.