Papers by Keyword: Liquid Environment

Abstract: This paper describes the development of a fatigue testing machine for small sized specimens in liquid environment. Since this type of testing machine is not available commercially, it has been designed, developed and built without any reference machine. The machine can operate tests on specimens with the shape of a solid cylinder with a diameter of 2 mm, a gage length of 4 mm and a total length of 34 mm. The testing machine consists of a testing stand, an environment vessel, a liquid cooling system and a test control system. Since the machine operates with combustible liquids, some safety devices have been also installed to prevent the machine from fire and explosion. The tests made for measuring the performance of the machine have been conducted on a specimen made by 440 stainless steel. The maximum applicable frequency by the testing machine is 100 Hz but only in a range of applied stress amplitude from 0 to 800 MPa. In 800 – 1200 MPa, the maximum frequency decreases down to 50 Hz with increase in the stress amplitude.

Abstract: The synthesis of multi-walled carbon nanotubes MWCNTs, carbon nanoshells, carbon nanoonions (CNOs), different types of carbon nanostructures and CaCO3 nanoparticles were performed using an arc-discharge method in mineral water. The structures of the synthesized nanostructures were visualized by scanning electron microscopy and transmission electron microscopy (TEM). Furthermore, ultraviolet-visible spectroscopy and thermo-gravimetric analysis (TGA) were used to determine the optical and thermal properties of the synthesized nanostructures. The TEM observations revealed that as-synthesized MWCNTs and CNOs have nominal diameters in the range of 10-20 nm and 30-50 nm, respectively. The CaCO3 nanoparticles were directly synthesized using arc discharge due to the presence of Ca minerals in the mineral water. The production rate of synthesized MWCNTs decreased when the arc current increased above 50 A, and the production rate of different nanoparticles increased with increasing arc current. The thermal-oxidative stability of the carbon nanostructures using TGA was explored separately under argon and oxygen atmospheres.