M.Sc. Tezi Görüntüleme

Student:	Gonul USTA
Supervisor:	Associate Professor
Department:	Metalürji ve Malzeme Mühendisliği
Institution:	Graduate School of Natural and Applied Sciences
University:	Karadeniz Technical University, Turkey

Title of the Thesis:	Investigation of Producing Rapidly Solidified Bronze Powder and Ribbon by Water Jet Cooled Rotating Disc Atomization
Level:	M.Sc.
Acceptance Date:	18/12/2009
Number of Pages:	102
Registration Number:	i2113

Summary:

In this study, CuSn10 bronze alloy was atomized with water jet cooled rotating disc atomization method in high purity argon gas atmosphere and rapidly solidified powder and ribbon were produced. The effects of atomization parameters such as disc speed, disc fin number, surface roughness of the disc, flow rate and superheat of liquid metal on the properties of produced powders in terms of morphology, mean particle size and yield rate were investigated. Beyond this, the microstructure of produced powders and ribbons was also examined and cooling rates were calculated.

The mean particle sizes of the produced bronze powders were in the range of 100-250 µm depending on atomization parameters. The yield rate values obtained were in the range of 65-85%. The mean particle size of powders decreased and yield rate increased with increasing disc speed and disc fin number, increasing surface roughness of the disc, increasing superheat of liquid alloy and decreasing flow rate of liquid alloy. The smallest mean particle size and the highest powder yield rate were obtained by using ZrO2 material coated disc with four fins, 2 mm nozzle diameter of flow rate, 300 C superheat and 75 m/s disc speed. The typical shapes of produced bronze powders were mostly appeared in the shapes of sphere, rounded, ligamental, irregular and flaky, being dependent on the particle size. The cooling rate of produced powders was calculated as 5,82105 - 0,20103 K/s depending on cell size. Apart from powder, bronze alloy ribbons with the size of 15-95 µm thickness, 3-6 mm width and 45-72 mm length were produced with using uncoated disc with two fins. The ribbon thickness decreased with increasing disc speed and decreasing liquid alloy flow rate. The cooling rate of produced ribbons were in the range of 3x106 - 2,8x105 K/s depending on ribbon thickness.

Key Words: Rotating Disc Atomization, Rapid Solidification, Powder Production, Ribbon

Production, CuSn10 Bronze Powder