1. Introduction Silicon nitride is a chemical compound of the elements silicon and nitrogen with the formula Si3N4. Silicon nitride (Si3N4) was developed in during the period of 1960-1970 in a aim to search for fully dense, high strength and high toughness materials. The particular focus for its development was to replace metals with ceramics in advanced turbine and reciprocating engine applications to give higher operating temperatures and efficiencies. Even though the final goal of a ceramic engine has never been achieved, but silicon nitride has been used in a number of industrial applications, such as engine components, bearings and cutting tools. Silicon nitride has better high temperature capabilities than most metals with adding retention of high strength and creep resistance with oxidation resistance. In accumulation, its low thermal expansion coefficient gives good thermal shock resistance comparing with other ceramic materials. It is the most thermodynamically stable compound. 2. Production Pure silicon nitride is difficult to produce as a fully dense material. This covalently bonded material does not readily sinter and cannot be heated over 1850oC as it dissociates into silicon and nitrogen at these …show more content…
Typical densities are in the range of 2300 – 2700 kg.m-3 compared with 3200 kg.m-3 for hot pressed and sintered silicon nitride. Higher densities can be achieved by HPSN and SSN methods. However, the higher density gives the materials with better physical properties and so they are used in more demanding applications. The nitridation produces only a small volume change, which means that RBSN components do not need to be machined after fabrication and complex near net shapes can be produced in a single process
In September 1959 DiVita asked 2nd Lt. Richard Sturzebecher if he knew of a way to produce a strong glass fiber that would be capable of carrying a light signal. Sturzebecher had melted 3 triaxil glass systems together for his senior exam at Alfred University. In his exam, Sturzebecher had used SiO2, a glass powder produced by Corning. Whenever he had tried to look at the substance through a microscope he would end up with headache. Sturzebecher realized that these headaches came from the high amounts of white light produced from the microscopes light that was reflected through the eyepiece via the SiO2. SiO2 would be an ideal substance for transmitting strong light signals if it could be developed into a strong fibre.
But here we discuss only Chemical Vapor Deposition which helps for mass production of CNTs. The process discussed in this article is otherwise a mimicking of the Chemical Vapor Deposition.
Nitinol is a metal amalgam made up of nickel and titanium, these two components are available in equivalent nuclear rate. Nitinol amalgams show two firmly related and extraordinary properties: shape memory effect (SME) and superelasticity. Shape memory is the capacity of nitinol to experience misshapening at one temperature, then recuperate its unique, undeformed shape after warming over its "change temperature". Superelasticity happens at a restricted temperature extend simply over its change temperature; for this situation, no warming is important to bring about the undeformed shape to recuperate, and the material shows tremendous flexibility, some 10-30 times that of standard metal.
Some ceramics are used in orthopaedic applications such as bone repair, bone augmentation and joint replacement but their use in this field is not as extensive or widespread as metals and polymers because ceramics have poor fracture toughness. This severely limits the use of ceramics in load bearing applications (Davis, 2003).
3D printing is primarily for rapid part prototyping and small-run production in a variety of industries. In the meantime, the term additive manufacturing has come to represent the use of 3D printing to create metallic components and final parts, differentiating from conventional subtractive manufacturing processes. 3D printing uses computer-generated designs to create build paths that reproduce a digital model through consolidation of materials with an energy source. The process typically uses a laser, a binder or an electron beam that solidifies material as it is directed along scanned over a pre-placed layer or the build path of material. This method has been used successfully with metals, polymers and ceramics. Metals are still in their infancy in terms of finished part production. Metallic parts produced with 3D printing frequently require additio...
The bond distance of Fe-O was found to be decreasing with each increase in temperature, as indicated in figure 3. This was observed to be similar to the Si-O bond distance in the SiO2. This is due to the increasing in disruption at high temperature arise from the excitation of energy levels and amplitude vibrations.
In basic research, special model systems are needed for quantitative investigations of the relevant and fundamental processes in thin film materials science. In particular, these model systems enable the investigation of i.e. nucleation and growth processes, solid state reactions, the thermal and mechanical stability of thin film systems and phase boundaries. Results of combined experimental and theoretical investigations are a prerequisite for the development of new thin film systems and tailoring of their microstructure and performance.
Physical and Chemical Properties (2001, January 16). In Material Safety Data Sheet. Retrieved March 19, 2014, from http://avogadro.chem.iastate.edu/msds/nh4no3.htm
Titanium shows a high strength-weight ratio and has exceptional corrosion resistance. Titanium alloys have received considerable interest recently due to their wide range of applications in the aerospace, automotive and medical industries. The most common titanium alloy is Ti6Al4V, which belongs to the α+ β alloy group. However titanium alloys are difficult to machine due to their low modules of elasticity. Titanium is a poor conductor of heat, its thermal conductivity is about 1/6 that of steel. Heat, generated by the cutting action, does not dissipate quickly; therefore, most of the heat is concentrated on the cutting edge and the tool face [1]. Titanium has a strong alloying tendency or chemical reactivity with materials in the cutting tools and also reacts with oxygen and nitrogen in air at tool operating temperatures. This causes galling, welding, and smearing along with rapid destruction of the cutting tool [1].
Have you ever had a question about the History of Chemistry, because I just had one recently about the invention of Pepto-Bismol. This invention of Pepto-Bismol was a key invention to the society because this helped people cure their rare disease in the late nineteenth century that people called diarrhea. Today, I am going to take you on an adventure through time that was the late eighteenth century to the early nineteenth century and you will come to see that Pepto-Bismol was an amazing invention. Let’s start with the beginning stages of the creation of Pepto-Bismol.
Copper and copper alloys, such as bronze, brass, leaded brass are commonly used in friction parts of machines, as bearing liners, bushings, and water with gas fittings. Properties such as high strength and ductility, fatigue strength, wear resistance and machinability are necessary for these materials. Obtaining such properties is possible by creating submicrocrystalline and nanocrystalline structures in the materials [1]. The most common copper alloys are the brasses for which zinc, as a substitutional impurity, is the superior alloying element. Some of the common brasses are yellow, naval, and cartridge brass and gilding metal. Some of the common uses for brass alloys include jewelry, cartridge parts, automotive radiators, musical instruments,
It is said that each one of us has at least twenty microcontrollers in our houses or workplaces. According to a survey, there are more than two billion microcontrollers being manufactured annually. Everybody around the world could not even consider a day without these electronic components (John, 2013). Today, the world is evolving towards a computer-based and technology-dependent environment. Computers, robots and machines could be seen everywhere. Buildings and homes are now majorly powered and managed by electronic devices. All these are made possible by a present day innovation—the microcontroller like the Arduino. The Arduino is a flexible and powerful yet user-friendly microcontroller used in electronic projects to interpret and evaluate data and provide the programmed output in reference to the evaluation results.
Engineer dates back to 1325 when an engine’er, someone who operates an engine, was referred to by a conductor as an engineer. (Ford)
In summary, the rate of cooling from the austenite phase is the main determinant of final structure and properties.