Two kinds of mesocarbon microbeads (MCMBs) with different chemical composition have been synthesized. The MCMBs were molded and heat treated at temperatures above 2000 °C to obtain graphite blocks. The effects of chemical composition of MCMBs on the pore morphology, carbon texture and thermal properties of the derived graphite blocks have been explored. The pore morphology was investigated by small angle X-ray scattering technique and a graphitization-induced morphology transition was observed. When the graphitic crystallite size exceeded a threshold value, the association of crystallites and migration of randomly distributed pores took place extensively. For the graphite blocks made of MCMBs which had light components with higher aromaticity value, the growth of crystallites caused a significant enhancement in thermal conductivity for the specimens. However, for the other kind of MCMBs, their light components tended to form solid porous carbon texture after graphitization, and the thermal conductivity coefficients of their graphite blocks could only increase slightly as crystallites grew. It was suggested that the thermal resistance at the granule’s boundary became noticeable in the latter case and thus the growth of thermal conductivity coefficients was prominently hindered.
SiAlON-based ceramics are some of the most typical ceramic materials used as cutting tools for HRSA(Heat Resistant Super-Alloys). SiAlON can be fabricated using ceramic processing, such as mixing, granulation, compaction, and sintering. Spray drying is a widely-used method for producing a granular powder of controlled morphology and size with flowability. In this study, we report a systematic investigation aimed at optimizing spherical granule morphology by controlling spray-drying parameters such as gas flow and feed rate. Before spray drying, the viscosities of the raw material slurries were also optimized with the amount of dispersant added.
In a previous study, it was reported that enzymatic hydrolysis under pressurization could be a new method which could produce arginine dipeptide and free amino acid in anchovy hydrolysate as salty enhancer at optimal condition. Powder is more efficient than liquid in terms of transport and storage stability. For the purpose of producing spray dried powder of various salt contents was investigated the effect of different salt concentration of anchovy hydrolysate on spray dried powder properties. The anchovy hydrolysate of various salt contents(in the range of approximately 0.7- 19.8% w/w) prepared adding the fish sauce (Dae-Young fish market) at inlet drying air temperatures of 120°C and 140°C. The process yield and physicochemical properties such as moisture content, bulk density, hygroscopicity and the morphology (EDS, XPS, XRD) of the anchovy hydrolysate powder was measured. The glass transition temperatures (Tg) of the powders equilibrated under various water activities were determined using a differential scanning calorimeter (DSC). Different drying conditions and salt concentration could generate anchovy hydrolysate powders with different process yield, bulk density and moisture content. The spray-dried anchovy hydrolysate powder was confirmed by XRD to be a mixture of an amorphous substances and crystalline salts. The energy dispersive X-ray spectrometer (EDS) and X-Ray Photoelectron Spectroscopy (XPS) analysis demonstrated that the surface NaCl concentration of the powders increased with an increasing drying air temperature. Increasing moisture adsorption of the anchovy hydrolysate powders resulted in a Tg reduction. It is suggested that producing spray dried anchovy hydrolysate for the industrial use is the use of the feed salt concentration of not lower than % w/w and inlet air temperature at 120°C, 140°C
Cold spray deposition using Titanium powder was carried out to investigate the effects of powder morphology and powder preheating on the coating properties such as porosity and hardness. The in-flight particle velocity of Ti powder in cold spray process was directly measured using the PIV (particle image velocimetry) equipment. Two types of powders (spherical and irregular ones) were used to manufacture cold sprayed coating layer. The results showed that the irregular morphology particle appeared higher in-flight particle velocity than that of the spherical one under the same process condition. The coating layer using irregular morphology powder represented lower porosity level and higher hardness. Two different preheating conditions (no preheating and preheating at ) were used in the process of cold spraying. The porosity decreased and the hardness increased by conducting preheating at . It was found that the coating properties using different preheating conditions were dependent not on the particle velocity but on the deformation temperature of particle. The deposition mechanism of particles in cold spray process was also discussed based on the experimental results of in flight-particle velocity.