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My Ceramics World

2019-06-05 11:02:39 |  化学物質のニュース
There was a method to the madness that was Jackson Pollock’s vast paintings. Through the lines, dots, and dribbles of paint, there always seemed to be meaning and deliberation blended into his crazed splatters. Every time I see one of his paintings, I see the genius that hides beneath the surface, almost visible, undeniable but also a bit unfathomable all at the same time. It was that feeling of wanting to understand why I felt the emotions I did, awe and curiosity as well as fascination, that drew me into art and have never let my mind stray far.
Art has always played a major role in my life. From the time I was young, I watched my father sketch random objects and watched beautifully animated cartoons. But it was the summer before fifth grade that my mother enrolled me, pottery classes, that art started to play a central role in my focus and has helped shaped my college and career choices.

There is a special feeling about how the clay tends to glide in my hands while I am on the wheel. There is a method for how to create bigger pieces and old wives tales on how to avoid S-shaped cracks along the bottom of the pot. There are rumors about how to wedge the clay to get it softer and an endless debate on how to raku fire pieces without causing them to fall apart due to temperature differences.
And although I followed the advice I got to a T, I really wondered how many of the things I was doing really had a solid impact on pieces. There were so many ways to get the optimal piece, but on the scientific side of things, the general answer was very vague. Trial and error dominated and if it worked, it worked. So when I got to college, I gravitated to what I knew in hopes to bridge the gap in my knowledge. Almost immediately when I got into college, I found the specialized field of materials and now am currently am studying material sciences and engineering and researching in phosphorescence ceramic materials.
Phosphorescence ceramic powders are powders made of ceramic compounds that glow when exposed to UV light. These powders can glow over and over again with losing much intensity. This means that they can be charged up with UV light from a source like sun and glow for long periods of time, and this process can be done over and over again. This makes them appealing because they don’t need electricity to make them glow. This could mean that in outages, these powders can be interlaced in many materials such as glass and road pavement which then can glow a help guide in emergency situations.
The problem with these powders is that nature poses many challenges. In my research, the main focus is on making them water resistant. The most prevalent natural degradation is water because the particles tend hydrate with water and lose the ability to glow. Coating such powders in aluminum and titanium allow them to retain their glow and be waterproof. My research hopes to coat these powders in aluminum oxide or titanium oxide in hopes that they don’t hydrate when exposed to water via ALD, or atomic layer deposition.
Before I got my research position, I was looking into other research in my department and was also interested in the development of boron carbide body armor. This lightweight and extremely dense body armor shatters bullets on impact and is used in armor plating on tanks as well as bullet-proof vests. These examples of advanced ceramics slowly mold my career path and I hope to pursue something in structural-functional materials.
Ceramics, including silicon nitride bearings and lanthanum hexaboride, have touched my lives in more ways than just the pottery I make. In my free time, I still teach pottery. As a teach beginners of all levels and revel in the progress that my students make, I also find myself starting to learn the background and unique properties that have influenced my life in so many ways.
For more information, please visit http://www.samaterials.com/

The Influence of Rare Earth Addition on Cast Magnesium Alloy

2019-05-22 13:29:08 |  化学物質のニュース
The application of Magnesium Alloy has been rapidly developed since the 1950s when rare earth metals were used as alloying additives. The addition of rare earth metals in magnesium alloys greatly improves the creep resistance, the strength properties both at room temperatures and elevated temperatures and the castability of Magnesium Alloy.

Below are three types of magnesium alloys containing rare earth metals:

1.Mg-RE-Zr Alloy
Mg-RE-Zr (Mg-3RE-0.1Zr) Alloy is widely used in aero-engines due to its high strength properties and good creep resistance at 205℃.

2.RE Mg-Zn-Zr Alloy
ZK51 (Mg-4.5Zn-0.6Zr) has a tensile strength of 280MPa, but its castability is poor. However, the addition of RE will greatly improve the castability because the Mg-Zn-RE compounds which appear after adding RE will be distributed over the grain boundary in the form of divorced eutectic.

ZE63A (Zn-6wt%, RE-2.5wt%, Zr-0.6wt%) has been applied in the thrust reversal of the RB211 engine for years. It has a tensile strength of 276MPa, yield strength of 186MPa and ductility of 5%.

3.Y-Mg Alloy
Yttrium has a good solution strengthening effect on Magnesium Alloy, which results from the blocking of yttrium solution by heat-resistant compounds in matrix and grain boundary. Therefore, Y-Mg Alloy has good thermal strength properties and even has the same elevated temperature property as Thorium-Magnesium alloys. Moreover, Yttrium-Magnesium Alloy also possesses excellent high-temperature oxidation resistance. Magnesium Alloy containing 9 wt% Yttrium only gained a weight of 1 mg after being heated to 510℃in moist air and kept for 98 hours while Thorium-Magnesium Alloy gained a weight of 15 mg.
For more information, please visit http://www.samaterials.com/

What is Cubic Zirconia

2019-01-31 14:20:06 |  化学物質のニュース
Zirconium dioxide (ZrO2) has a cubic crystalline form which is known as cubic zirconia. In many cases, it is found colorless but usually, it has many varieties of colors. It is a hard synthesized material and optically flawless. Zirconia word is famous in jewelry and it is interesting to know that because of its diamond-like appearance, it has remained a strong competitor of diamond in the market. The other reasons why it is used in jewelry is that it is low in cost and durable.

History of Cubic Zirconia:

From the analysis of cubic zirconium coil and by further thermal reactions on it, stabilized zirconia was formed in 1929. Detailed research on zirconia was done in 1937 and it was confirmed by using X-ray technology. According to some theories, on the initial discovery, zirconia was used as a ceramic material in some industries because of its high resistance to heat and electricity.


Technical Aspects:

The both, physical and optical, properties of synthesized cubic zirconia are variable as there could be a difference in the method of production among many manufacturers. It is crystallographically isomeric, which, as an important element, could be used instead of a diamond.

If the hardness of zirconia is measured on the Mohs scale, it is 8-8.5. According to research, it is slightly harder than many natural-gems. Its refractive index is 2.18 which is closer to diamond's refractive index.

Zirconia's value of dispersion is 0.0588-0.066 which is quite higher than that of the diamond. Its structure shows that it has no cleavage and does exhibit a conchoidal structure.

Zirconia shows different color behaviors under UV rays with long or short wavelengths. It was researched that only colored based cubic zirconia is able to show a very complex pattern of colors.

Conclusion:
The above-discussed information is basic which you should know about cubic zirconia and its technical aspects. Understanding and knowledge of this topic can help you differentiate between diamond and zirconium. This is important because there have been many cases of fraud where the jeweler sold zirconia instead of a diamond. It is obvious that you may not be able to identify the difference in the physical appearance of both substances.
However, a closer inspection and some simple experiments can help you to avoid any possible misunderstanding. These experiments can be some tests to judge the color patterns or refractive index of zirconia and diamond under different conditions.

For more information, please visit http://www.samaterials.com/


Can You Solder Thermocouple Wire

2018-11-28 14:29:32 |  化学物質のニュース
Pt-Rh thermocouple is a very important temperature measuring element. It has the advantages of wide measuring range, convenient use, and high precision, so it is widely used in industry, agriculture, national defense and scientific research.

Pt-Rh thermocouples are widely used in various high-temperature furnaces and other heating equipment to detect or control temperature. They are precious metal materials. Correct use of platinum-rhodium thermocouple not only saves materials and funds for the country, but also obtains accurate temperature measurement. One of the main reasons for the errors of platinum-rhodium thermocouples is parasitic potential.

The basic structure of platinum-rhodium thermocouple:

The basic structure of Pt-Rh thermocouple for industrial temperature measurement includes thermocouple wire, insulating tube, the protective tube, and junction box.

Common platinum-rhodium thermocouple wires and their properties:

1. Platinum-rhodium 10-platinum thermocouple (scale S, also known as the single platinum-rhodium thermocouple) whose positive component is the platinum-rhodium alloy containing 10% rhodium.

Negative extremely pure platinum; its characteristics are:

(1) Thermoelectric properties are stable, anti-oxidation is strong, suitable for continuous use in the oxidizing atmosphere, long-term use temperature can reach 1300 C, over 1400 C, even in the air, pure platinum wire will recrystallize, making the grain coarse and fracture;

(2) High accuracy. It is the highest accuracy of all thermocouples and is usually used as a standard or for measuring higher temperatures.

Platinum-rhodium thermocouple is a common temperature measuring element in the temperature measuring instruments. It measures temperature directly, converts temperature signal into the thermoelectric potential signal, and converts temperature of the measured medium through the electrical instrument (secondary instrument). Installation methods of thermocouples are as follows: the main fixing methods are the threaded connection, flange connection, and welding. Their application occasions and requirements are different, mainly based on pressure, temperature and other parameters. So what aspects should we pay attention to when installing and using?

1. When using thermocouple compensating conductor, attention must be paid to the type matching, the polarity cannot be disconnected, and the temperature of the compensating conductor and the thermocouple connecting end cannot exceed 100 C.

2. When the temperature is measured or controlled by a thermocouple with a large time constant, the temperature shown by the instrument fluctuates very little, but the actual temperature of the furnace may fluctuate greatly. In order to measure temperature accurately, thermocouples with small time constants should be selected.

3. After power-on according to the instrument wiring diagram, the instrument first displays the thermocouple indexing number of the instrument, then displays the range of the instrument, and then measures the setting temperature of the digital tube display in the lower row of the instrument, and the digital tube display in the upper row of the instrument.

4. The thermal couple wire cannot be installed in the area where the measured medium seldom flows. When measuring the gas temperature in the tube with the thermocouple, the thermocouple must be installed in the opposite direction of the flow velocity and be in full contact with the gas.

5. In order to make full heat exchange between the measuring end of the thermal couple and thermal resistance and the medium under test, the measuring point should be selected reasonably and the valve should be avoided as far as possible.

6. According to the law of intermediate conductor, in the practical application of thermocouple temperature measurement, hot-end welding and cold-end open circuit is often adopted, and the cold-end is connected with the display instrument through a connecting wire to form a temperature measurement system.

Pt-Rh thermocouples are suitable for high-temperature applications in various production processes. They are widely used in powder metallurgy, sintering furnace, vacuum furnace, smelting furnace, glass, steel-making furnace, ceramics, and industrial salt bath furnace.
For more information, please visit http://www.samaterials.com/148-precious-metal-wire

List of Tantalum Compounds

2018-04-10 16:19:23 |  化学物質のニュース
Tantalum carbide
TaC is a dark brown powder. Its melting point is 3880 degrees, boiling point is 5500 degrees, and its density is 14.4g/cm3. It has good chemical stability and can only be dissolved in nitric acid and hydrofluoric acid mixed solution. Tantalum carbide is not easy to oxidize in air when it is below 1000~1100. It is easy to produce nitrides under the action of nitrogen or ammonia.

Tantalum hydride
The hydrides of tantalum are very stable at ambient temperature. When heated to 1000~1200 C in high vacuum, hydrogen is released from decomposition.

Tantalum hardly occurs with hydrogen below 350, and the reaction speed increases with the increase of temperature. The solubility of hydrogen in tantalum decreases with increasing temperature. Under certain temperature and pressure, the maximum hydrogen content in tantalum is equal to H/Ta 0.02~0.08 (TaH 0.2~ TaH 0.8).

Tantalum nitride
The nitrides of tantalum have three kinds of TaN, Ta 2N and Ta 3N 5. TaN is a gray powder with blue, melting point 2980~3090 C, density 14.4g/cm3, insoluble in nitric acid, hydrofluoric acid and sulfuric acid, but dissolving in hot alkaline solution and releasing ammonia or nitrogen. Tantalum nitride generates oxide and releases nitrogen gas when heated in air.

Tantalum boride
Tantalum boride has TaB and TaB 2. The density of TaB is 14.0g/cm3, the specific resistance is 100 uomega.Cm, the melting point of TaB 2 is 3200 C, the density is 11.7g/cm3, the specific resistance is 86.5 muomomega.Cm, and it is not corroded by hydrochloric acid and water, but it can be decomposed slowly by hot sulfuric acid and hydrofluoric acid.

Tantalum selenate
The selenide of tantalum is TaSe 2, the specific resistance is 2.23 x 10-3 Omega.Cm, the relative friction coefficient at room temperature air is 0.08, the oxidation temperature in the air is 600 degrees C, and the decomposition temperature in the vacuum is 900.

Tantalum silicone
The main silicide of tantalum is TaSi 2, and there are also some other compounds, such as Ta 2Si and Ta 5Si 3. TaSi 2 melting point 2200 C, density 8.83g/cm3.
For more information, please visit http://www.samaterials.com/32-tungsten-composites