As mentioned already magnetron sputtering has become the process of choice for deposition of a wide range of industrial coatings. When power is supplied to the magnetron, a negative voltage of typically -300 V or more is applied to the target. This attracts ions to the target surface at speed. When they collide with the surface two important processes take place: atoms are knocked out of the target surface. These sputtered atoms are neutrally charged and so are unaffected by the magnetic trap. These sputtered atoms collide with the substrates to be coated and form an extremely adherent coating. Generally the formation of the coating consists of four-stage process, nucleation, island growth, coalescence and finally continuous growth. The second important process that occurs when an ion collides with the target surface is that electrons are emitted. The light and negatively charged electrons when they leave the surface are affected by the combination of …show more content…
The schematic diagram of a magnetron gun is shown in Figure 11. Magnetron sputtering creates most uniform and most cost effective films. During magnetron sputtering energetic electron escape from the primary magnetic trap between the inner and outer magnets, and in the balanced magnetic field these electrons go to the anode. It is the primary trap that is responsible for the formation of the dense plasma directly in front of the sputtering target. A magnetron consists of a plate of the material of which all or part of the coating is consisting with magnets arranged behind it with alternating polarity. Well defined plasma forms near the surface of the target. Ejected electrons that are able to leave the near cathode region expend their energies locally increasing the probability of ionization near the target and thereby the sputtering rate. This is the result of the E x B
During the years leading up to and during the American Civil War there were a number of advancements in firearms technology. This paper will focus on a few of those advancements, namely the inventions of the Minié ball, the Spencer and Henry repeating rifles, and of the Gatling gun.
The gun was a hand-crank-operated weapon with six barrels revolving around a central shaft. Having a gun that revolves was very difficult because the barrels would not always line up correctly when being fired. The original gun was actually designed to fire the standard military issue paper cartridge of the day, .58 caliber. A .58 caliber bullet has a diameter of an inch and is capable of damaging anything it hits. The paper cartridge was placed inside a steel or brass chamber with a percussion nipple on the back end just like the muzzle loading rifles and pistols of there time.
It should be noted that there are many different ways that are employed to get a marker to shoot a paintball out of the marker. Nearly every brand of marker has a different firing system. All have several things in common. They all have some sort of tank with compressed air or C02 or Nitrogen. Then they usually have sort of bolt and hammer system which is cocked back and held in place by a sear which compresses a spring. When the trigger is pulled it releases the sear. The restoring force of the spring pushes the bolt and the hammer forward starting the paintball moving then the C02 is released propelling the ball outward.
...the mass spectrometer. This is called an electron impact source. Gases and volatile liquid samples are allowed to leak into the ion source from a reservoir. Non-volatile solids and liquids may be introduced directly. Cations formed by the electron bombardment (red dots) are pushed away by a charged repeller plate (anions are attracted to it), and accelerated toward other electrodes, having slits through which the ions pass as a beam. Some of these ions fragment into smaller cations and neutral fragments. A perpendicular magnetic field deflects the ion beam in an arc whose radius is inversely proportional to the mass of each ion. Lighter ions are deflected more than heavier ions. By varying the strength of the magnetic field, ions of different mass can be focused progressively on a detector fixed at the end of a curved tube. Because the mass of each individual ion
size. The muzzle velocity is at 2,800ft/sec (853m/sec) with also a rate of fire 725 rounds per
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.
Microelectromechanical Systems (MEMS) are systems that are designed on a micro metre scale and have become more popular as the demand for devices to get smaller has increased. The main uses of these systems are for sensors, such as accelerometers and gyroscopes and other such devices like microscopy and inkjet nozzles for example. There are many materials that can be used for MEMS as the cost of the material is almost eradicated due to the micro size of the systems being produced. This brings materials such as gold, platinum and diamond can be used, as these materials have some properties which are very desirable for a MEM systems. The most common material that is currently used in MEMS is silicon and silicon based compounds as they possess many good properties for MEMS production. Most of the materials chosen for MEMS are semiconductor materials Figure 1 shows the properties of commonly used materials.
When the high voltage circuit is activated, the x-ray machine beeps, the electrons travel from the filament to the target, heat is produced, and the electrons at the cathode fire across the tube and hit the target at the anode.
A gun has a high muzzle velocity and a very flat trajectory. Normally a gun is used in a direct fire mode where the target can be seen and penetration is desirable. Good targets for a gun would be things like brick or earth forts, ships, buildings, and targets in tree lines. Howitzers have a somewhat lower muzzle velocity and arc their shells onto a target. They are used in both direct fire and indirect fire mode.
...rounds per minute, all with just the pull of the trigger. The recoil operation was a milestone in machine gun development. Warfare had truly changed. “Point a machine, and killing men was like killing bugs” (Chivers, 2010, p.85). It used new forms of cartridges which were placed on a belt that was automatically fed into the gun via the recoil operation.
1. Deposition Processes: One of the basic building blocks in MEMS processing is the ability to deposit thin films of material. This is achieved either through the processes like PVD or CVD.
...h cesium ions and then to focus it into a fast moving beam. The ions that are produced become negative, which helps prevents the confusion of Carbon-14 with Nitrogen-14 since Nitrogen does not have a negative ion. The first magnet is used to select ions with an atomic mass of fourteen. The ions then enter the accelerator. As they travel to the terminal, they are accelerated to an incredible speed so when they collide with the gas molecules, all of the molecular ions are broken up and most of the carbon ions have four electrons removed, turning them into Carbon3+ ions. The second magnet selects ions with the speed expected for the Carbon-14 ion and a filter makes sure their momentum is also right. Finally, the filtered Carbon-14 ions enter the detector where their speed and energy are checked so that the number of Carbon-14 ions in the sample can be counted (Oxford).
There is a layer of magnetic material on the surface of the platter. Today, thin-film media is used here. Thin-film media is a microscopic. layer of pure metal bonded to the substrate surface through an interim. layer.
Corrosion may be defined as the deterioration of a material due to a reaction with the environment around it. Metals corrode because we use them in environments that are chemically unstable. Very few metal are found in nature in their metallic state such as copper, gold and silver . All other metals are processed from minerals or ores into metals which are innately unstable in their environments. These unstable metals have a tendency to revert to their more stable mineral forms. Some metals form protective ceramic films (passive films) on their surfaces and these prevent, or slow down, their corrosion process. We can prevent corrosion by using metals that form naturally protective passive films, but these alloys are usually expensive, so we have developed other means of corrosion control. That are discussed later in this paper.
?Robotics will boost quality and transfer efficiency levels.? Coatings (Jul.-Aug. 1991): 66 InfoTrac. Online. Nov. 2002. .