Kun Yu Zhao

Synthesis of Ni0.6Cu0.4Fe2O4 Ferrite Fine Powder Using Egg White Method

Polycrystalline ferrites powders samples: Ni0.6Cu0.4Fe2O4 were synthesized by using metal nitrates and freshly extracted egg white, all the samples were sintered at 500°C,520°C, 550°C, 580°C and 600°C for 3h,6h,9h, respectively. The better synthesis conditions were investigated by analyzed the effect of sintering temperature and soaking time on structural, grain size and magnetic properties using X-ray diffraction (XRD), laser grain size analyzer (LPSA) and vibrating sample magnetometer (VSM). From the above analysis, the better synthesis conditions is set two insulation work steps: First at 240°C for 1h, then heating to 440°C for 2h, finally sintering at between 520°C and 550°C for 6h.

Synthesis and Properties of Ca3Co4-xCuxO9 (0≤x≤1.4)

Ca3Co4xCuxO9 (0x1.4) misfit-layered thermoelectric oxides were prepared by traditional solid-state reaction method which cost less, operate easer, may produce Ca3Co4O9 on large scale. XRD study shows that we obtain Ca3Co4O9 major phase in series Ca3Co4xCuxO9 (0x1.4) samples which were sintered at the highest temperature 880°C for 8h by two steps. Metallographic microscopic analysis indicates that some samples grain size range at 2~4μm which were doped less Cu. Doping Cu in different way experiment suggests that Ca3Co4xCuxO9 (x=0.4) sample has lower electric resistivity while Ca3Co4O9+5%Cu samples resistivity increases, compared with Ca3Co4O9 (x=0). The article infers that Ca3Co4xCuxO9 (0x0.4) can decrease the electric resistivity of Ca3Co4O9.

Effect of Ca Doping on Crystal Structure of the Misfit-Layered Bi-Sr-Co-O Thermoelectric Materials

The series of Bi-Sr-Co-O thermoelectric materials Bi2Sr2Co2Oy (BC-2202), Bi2SrCaCo2Oy (BC-2112), Bi2Sr2CaCo2Oy (BC-2212) were prepared by conventional solid-reaction process. The crystal structure of Bi-Sr-Co-O compound were analyzed by XRD and TEM. The results show that the diffraction peak shift to the high angle, the interlayer spacing decrease with the Ca doping, however, the diffracion peaks of BC-2212 weak with the sintering temperature increased. The reason for that is some Ca can not enter the lattice while the Ca improved by whole mole.

Effect of Cl- Content, pH Value and CO2 on Electrochemical Corrosion Features of Cr15 Super Martensitic Stainless Steel

The corrosion behavior of a Cr15 super martensitic stainless steel (Cr15 SMSS) was investigated in NaCl solutions by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Effects of Cl- content, pH value and saturated CO2 on corrosion were sdudied. It was found that the parameters of maintaining passivity current density (ip), the critical pitting potential (Eb) and charge transfer resistance (Rt) of Cr15 SMSS varied widely under different conditions. The corrosion resistance of Cr15 SMSS decrease with increasing Cl- concentration and lowering pH value. Both ip and Eb increase for Cr15 SMSS in CO2-saturated NaCl solution, which verified that the CO2 in NaCl solution can result in lower pitting sensitivity and higher uniform corrosion rate to Cr15 SMSS.

Study on Color Change of Brown Sapphire in Changle, Shandong

Most Shandong sapphires color are indigo blue, green and brown yellow, these deep color influence their commercial value. This paper makes a comparative study of the traditional heat treatment and heat diffusion treatment on brown series of sapphire of Shandong. The results show that heat treatment is helpful to improve the transparency of Shandong sapphire, but cannot produce ideal color, and it also has no obvious effect on its internal features. However, diffusion treatments after adding TiO2 can obtain comparatively ideal color, which is blue-green to blue. And the transparency and dark mineral inclusions are improved.

Effect of Tempering Process on Structure and Properties of Super Martensitic Stainless Steel

Two types of super martensitic stainless steels (Cr13 and Cr15) were designed. The effect of tempering process on their microstructure, mechanical properties and corrosion resistance was studied. The results showed that the main microstructure of tested steels was tempered martensite and a small number of reversed austenite when specimens were tempered in temperature range of 550-750°C. The variation of mechanical properties corresponded to the austenite volume fraction well. Both the two types of steels displayed a favorable comprehensive mechanical properties after tempering at 650°C, their product of strength and elongation reached to 18.44GPa•% and 18.44 GPa•% respectively. With the best heat treatment process,tempered at 650°C after quenching at 1050°C,the corrosion resistance of 2# steel is more better than 1# steel.

Influence of pH on the Electrochemical Bahavior of 00Cr15Ni7Mo2Cu2 Supermartensitic Stainless Steel in 3.5% NaCl Solutions

This objective is to study the influence of pH on the electrochemical behavior of 00Cr15Ni7Mo2Cu2 supermartensitic stainless steel in 3.5% NaCl solutions using potentiondynamic polarization technique, open circuit potential tests and electrochemical impedance spectroscopy (EIS).The study reveals that the pitting potential (Eb) is higher, the passivation current densities (ip) is lower and the electrochemical impedance increases with the pH. The results indicate that this stainless steel offer good pitting corrosion resistance with the pH increasing in 3.5% NaCl solutions.

Synthesis of the Thermoelectric Thin Films of Ca3Co4O9 and Ca3Co2O6 Using Pulsed-Laser Deposition Techniques

Thermoelectric ceramic targets of Ca3Co4O9 and Ca3Co2O6 were prepared by the sol-gel method. The technology and mechanism of synthesizing the thermoelectric thin films of Ca3Co4O9 and Ca3Co2O6 were investigated. The thin films of Ca3Co4O9 and Ca3Co2O6 were grown on (0001)-oriented (c-cut) Al2O3 substrates by pulsed-laser deposition techniques (PLD). Ca3Co4O9 thin films grown at substrate temperature of 700°C and 800 °C appear to be obviously c-axis-oriented. But the x-ray diffraction peak of Ca3Co2O6 thin films was not confirmed. Ca3Co4O9 thin films and Ca3Co2O6 thin films exhibited Ca elements and Co elements volatilization at high temperatures.

Effect of Heat Treatment on Microstructure and Properties of Cr15 Super Martensitic Stainless Steel

The microstructure and mechanical properties of Cr15 super martensitic stainless steel after different heat treatment were studied by SEM and XRD. The results show that the microstructure of steel A and B are lath martensite and retained austenite after quenching. The original austenite grain size increases with the increasing quenching temperature. The microstructure is composed by tempered martensite and reversed austenite after tempering. The amount of reversed austenite in both steels increases first and then decreases with the increasing tempering temperature. Both of the tested steels have the best mechanical properties at 650°C tempering temperature.

Effect of Chloric Ions and Temperature on the Pitting Corrosion Behavior of Supermartensitic Stainless Steel in CO2-Saturated Chloride Solution

Abstract. The pitting corrosion behavior of two kinds (W and Cu-free; W and Cu-bearing) of supermartensitic stainless steels (SMSS) were studied in CO2-saturated chloride solution with three chloric ion concentration: 21200, 50000, 100000ppm, and four different temperatures:19, 40, 60, 80°C by potentiodynamic polarization measurement. The results indicate that the pitting potential decreased with temperature increasing, and in a logarithmic relation with the chlorine concentration in both alloys. The pitting potential of supermartensitic stainless steel is increased by together adding tungsten and copper.