Cryogenics and "cold" or "freezing" applications,
Part Two
Using cryogenics for industrial purposes
Cryogenics is the study of how to get to low temperatures and of how materials behave when they get there. Besides the familiar temperature scales of Farenheit and Celsius (Centigrade), cryogenicists use other temperature scales, the Kelvin and Rankine temperature scales.
One interesting feature of materials at low temperatures is that the air condenses into a liquid. The two main gases in air are oxygen and nitrogen. Liquid oxygen, "lox" for short, is used in rocket propulsion. Liquid nitrogen is used as a coolant. Helium, which is much rarer than oxygen or nitrogen, is also used as a coolant.
The thermal treatment of metals must certainly be regarded as one of the most important developments of the industrial age. After more than a century, research continues into making metallic components stronger and more wear-resistant.
One of the more modern processes being used to treat metals (as well as other materials) is cryogenic tempering. While the science of heat treatment is well known and widely understood, the principles of cryogenic tempering remain a mystery to most people in industry.
Information regarding this process is full of contradictions and unanswered questions. Until recently, cryogenic tempering was viewed as having little value, due to the often brittle nature of the finished product. It is only since the development of computer modeled cooling and reheat curves that the true benefits of cryogenically treated materials have become available to industry and the general public.
Cryogenics consist of processes that cover a wide variety of subjects in low temperature engineering and research. Among the areas covered are:
- Applications of superconductivity: magnets, electronics, devices
- Superconductors and their properties
- Properties of materials: metals, alloys, composites, polymers, insulations
- New applications of cryogenic technology to processes, devices, machinery
- Refrigeration and liquefaction technology
- Thermodynamics
- Fluid properties and fluid mechanics
- Heat transfer
- Thermometry and measurement science
- Cryogenics in medicine
- Cryoelectronics
Cryogenics International's Deep Cryogenic Process.
- Deep cryogenics is the ultra low temperature processing of materials to enhance their desired metallurgical and structural properties.
- This is a temperature about -320º F, -196º C, or 77º K.
- These ultra cold temperatures are achieved using computer controls, a well-insulated treatment chamber and liquid nitrogen (LN2).
- Nitrogen is the gas that constitutes 78.03 percent of the air we breathe here on planet Earth.
- The liquid form, is the product of air separation, compression and liquefaction.
- Deep cryogenic systems are considered to be environmentally friendly and actually help reduce waste.
- Cryogenics International’s patented, controlled deep cryogenic treatment system and process is capable of treating a wide variety of materials, such as ferrous and non-ferrous metals, metallic alloys, carbides, plastics (including nylon and Teflon) and ceramics.
- The entire process takes between 36 to 74 hours, depending on the weight and type of material being treated.
- Strict computer control and proper processing profiles assure that optimum results will be achieved with no dimensional changes or chance of thermal shock.
- This special process is not a surface treatment; it affects the entire mass of the tool or component being treated, making it stronger throughout.
- This means the process keeps working even after numerous sharpenings.
- The hardness of the material treated is unaffected, while its strength is increased.
- These ultra-cold temperatures, will greatly increase the strength and wear life of all types of vehicle components, castings and cutting tools.
- In addition, other benefits include reduced maintenance, repairs and replacement of tools and components, reduced vibrations, rapid heat dissipation, and improved conductivity.
- Cryogenics is an exciting and important frontier that already has led to major discoveries and holds much future promise.
- In the case of steel and its alloys, cryogenic treatment removes the built-in kinetic energy of atoms, which is the energy of motion.
- There is a normal attraction between atoms that makes them want to get together.
- Their energy of motion keeps them apart unless that energy is removed by low temperature (cryogenic) cooling.
- After heat treatment of the dies, the final treatment transforms soft austenite into hard martensite.
- This transformation improves die surface wear and heat resistance; more parts can be produced before costly rework is required.
- This reduces the scrap rate of the casting, thus improving the production rate before rework of the tooling is required.
- Some examples of materials that are routinely cryogenically treated include: all types of steel, titanium, plastics, copper, nylon, aluminum, brass, various alloys, glass, and complete assemblies; such as, whole chain saws, engines, motors, etc.
The previous presentation consists of excerpts from a variety of sources; especially from
—Cryogenics International and American Cryogenics
If you would like to return to Cryogenics, Part 1, you may do it from here.
You will find many other words and definitions about cryo or "freezing, cold" words by going to the Latin-Greek Cross References or you may return to the word menu directory to see other vocabulary subjects.
|