Development of a PVD coating suitable to replace electroplated cadmium.
Background information
• Approximately one-fifth of ferrous metal produced was destroyed by corrosion every year.[1] Coating is a surface treatment widely used in almost all mechanical components. This process is taken to either increase the mechanical property or providing resistance to certain hazards which potentially damage to the component itself. Electric plating is one of the majorities coating method taken with mechanical component, cadmium is usually chosen for coating on tightening threads. For mechanical parts with threads such as screws and bolts, especially those parts needs a high performance and reliability, cadmium plating have several unique characteristics. Cadmium coating offers malleability, freedom from sticky and bulky corrosion products, can take torques by avoiding stick-slip.[2] Meanwhile its electric behaviour of Cadmium provides sacrificial protection of the metal inside such as steel. It has super enhanced corrosion resistivity against many kind of corrosion source such as salt atmosphere and chromates and gives a good lubricity and solderability characteristic.[3]
• However, as the cadmium plating provides a high performance, it also gives some negative effects. First, it’s an electroplating method, so solution treatment is taken. Wastes should be managed properly. So it becomes a potential pollution source. During the cadmium plating process, it seems most of environmental effect will be eliminated. However, in certain circumstances cadmium will cause a health hazard.[1] Both cadmium and chrome are carcinogens.[4]
• Physical Vapour deposition (PVD) is a relatively new method of placing coating on surfaces. It creating thin films on the surface by changing directly from gas/plasma to solid on the object. Usually PVD can provide a better performance and reduce the environment impacts. It also comes with problems such as high temperature, more complicate and well-controlled processes.
Objectives
• With the negative effect caused by cadmium, it is restricted in uses in some industries like automobile and electrical equipment by regulations of RoHS, WEEE and ELV. [5] So alternatives has been studied to deal with it. There are a large number of alternative coating could be used to replace cadmium, however, a lot of variables should be controlled. The properties of new coating should be similar to original cadmium. Variety of work and research need to be done before decide which one is used to replace.
• I divide the properties into 3 sections: mechanical properties, electrochemical properties and compatibilities. In mechanical properties, due to a wide application of cadmium coating is for fastener, the torque-tension properties is an important factor to consider as well as basic tensile strength and shear strength.
Combined with corrosion fatigue” (“Silver”).
We use metals to construct all kinds of structures, from bridges to skyscrapers to elevators. The strength as well as durability of materials that are crafted out of metal make the materials ideal not only for construction but also for many other applications.
For this scope of this assignment a study in the surface modification of a titanium alloy stem, used in a hip joint implant is going to be studied. A total hip joint implant consists of an articulating bearing basically the femoral head and cup and the stem. The stem is made from titanium alloy - Ti- 6Al- 4V where titanium is alloyed with aluminium and vanadium. When titanium is alloyed with these materials excellent properties are achieved such as high strength-to-weight ratio and exceptional corrosion resistance.2 However, this alloy gives poor tribological properties and tends to seize when it is subjected to sliding motion due to its low hardness of 36HRC.3 Several surface modification techniques are done on ti...
]. Some alloying elements sometimes added to impart special characteristics to brass. Lead, which is insoluble in copper alloys, used to improve machinability of leaded brass. However, Pb and Bi or other elements that are used to improve the machinability often deteriorate the low and high temperature ductility of brass [11]. The content of Pb element is varies between 2.5 and 3.5 %, which make the machining processes at high speed and good surface [12]. The solubility of lead in copper alloys is very low therefore, it is found in microstructure as dispersed globules all over the material. These globules lead act as a lubricant decreasing the friction coefficient between the tools and the materials by creating discontinuities of chip fragmentation. Therefore, it makes reducing in cutting force and then, the tools wear rate is minimized [13]. Different alloying elements help to improving the machinability are usually added to brass. The most common element using in this situation is lead, which improving the machinability with
A wide variety of coating alloys and wrought alloys can be prepared that give the metal greater strength, castability, or resistance to corrosion or high temperatures. Some new alloys can be used as armor plate for tanks, personnel carriers, and other military vehicles.
These include, high strength, low weight, high chemical resistance and high cut resistance. This material does not corrode or rust and is also unaffected when placed in or under water.
There is a debate that there is not actually one person who discovered cadmium. In the year 1817, a physician named Friedrich Stromeyer was one of the first ones who discovered cadmium. There were two more people named K.S.L. Hermann and J.C.H. Roloff that also discovered cadmium the same year. Cadmium is a naturally occurring metal. Cadmium was first discovered in vapors that came out of furnaces. It was found because zinc oxide was being roasted. Some of the early signs of it were in paints. People would want to make light colored paint darker so they would add cadmium, which would cause a brighter color. The pigments were primarily made from cadmium sulfide. Cadmium was also used for making leather gloves darker (Dartmouth, 2010). Cadmium toxicity is when a person eats food that has high levels, breathes in high levels, or drinks water with high levels of cadmium. Short-term or long-term exposer can be harmful...
In the first proposition, AVA Solar proposes to use solar energy in place of fossil fuel to reduce carbon emission rates. Although solar energy is an excellent method of generating clean “green” energy, has a popular appeal, and is typically given high marks in regards to “green” technology. This process raises concerns due to the use of cadmium, a toxic element used in solar panels that raises concerns about cancer. As an engineer, the first fundamental canon in the National Society of Professional Engineers (NSPE) codes of ethics is, “Engineers, in the fulfillment of their professional duties, shall hold paramount the safety, health, and welfare of the public”. Therefore, an engineer’s moral obligation is to not create or innovate something that is going to harm people. However, as the American Society of Civil Engineers (ASCE) code, states that “Engineers should be committed to improving the environment, to enhance the quality of life” (sec 1.f). In another ASCE document, “The role of an engineer is sustainable development”. As a result, an engineer in his decision should consider both the NSPE first code of ethics and also follow the ASCE code.
Stainless steel, especially, Austenitic stainless steel, because of their high corrosion resistance and customizable mechanical properties has become an indispensable part of the regularly evolving modern day technology. Stainless steels of various grades find applications in numerous fields starting from the household to the nuclear reactors; from food and beverage cans to construction of different automobile parts. The formation of impervious oxide layer on the surface makes it suitable for use in adverse environments such as sea water.
Take a hydrostatic sterilizer for example in which the flight bars and chains are made from aluminum, stainless steel or even carbon steel. These metals are surrounded by moist conditions in the form of steam or hot water. Once corroded, replacing the chains and bars is extremely expensive in the food industry. Both of these metals act as a cathode and an
BIBLIOGRAPHY Advantages to Aluminum. http://www.kaiserextrusion.com/advantage.html. November 28, 2000. Aluminum Facts. http://www.epa.gov/seahome/housewaste/src/alum.htm. November,28 2000. Bowman, Kenneth A. World Book Encyclopedia. "Aluminum." Chicago: World Book, Inc., 1992. Cobb, Cathy. Creations of Fire. New York: Plenum Press, 1995 Geary, Don. The Welder's Bible. Pensilvania: Tab Books, 1993. Knapp PhD, Brian. Aluminum. Connecticut: Grolier, 1996. Newmark, Dr. Ann. Chemistry. London: Dorling Kindersley, 1993. Walker, John R. Modern Metalworking. Illinois: The Goodheart-Willcox Company, Inc., 1985.
The purpose of this project was to discover how the pH level affects corrosion rate. The hypothesis was if the pH level affects the corrosion rate, then the lower the pH level is quicker the corrosion rate would be. This will happen because liquids below the pH level of 7 possess stronger acidic attributes. The effect of pH level on corrosion rate was determined by depositing a copper penny in each of three plastic cups, and then three different liquids by their pH levels, were assigned to be displaced into each cup formulating a chemical reaction to be observed. The results collected during this investigation contradicted with the intended result, this experiment was conducted to determine corrosion rate; Dana Puti Vingear (pH level: 4.5) 4 2/3 days, Tropicana Orange Juice (pH level 3.88) 6 1/3 days, and Sprite (pH level: 3.4) 8 days. The results showed that the hypothesis was refuted. This happened because the preconceived idea was that the liquid with the lowest pH level; Sprite, would have the quickest corrosion rate. Dana Puti Vinegar had the quickest corrosion rate proving the statement wrong, it was discovered that it contains ethanoic acid; acid containing twice the amount of carbon dioxide than a regular acid. To further understand this topic, future research could include; how does the amount of liquid incorporated affect the corrosion rate, how does the temperature of the liquid affect the corrosion rate, and how does the purity of iron affect the corrosion rate?
Song, J., Wang, L., Zibart, A.,& Koch, C. (2012). Corrosion protection of electrically conductive surfaces. Metals, 2/4, 450-477. doi:10.3390/met2040450
?Robotics will boost quality and transfer efficiency levels.? Coatings (Jul.-Aug. 1991): 66 InfoTrac. Online. Nov. 2002. .
There are 10 types of corrosion, General Attack Corrosion, Localized Corrosion, Galvanic Corrosion, Environmental Cracking, Flow-Assisted Corrosion (FAC), Intergranular corrosion, De-Alloying, Fretting corrosion, High-Temperature Corrosion. General attack corrosion attacks the entire surface of the metal and is caused by chemical or electrochemical reactions (Bell, 2017). Localized corrosion attacks only portions of a metal structure (Bell, 2017). Localized corrosion can be classified as 3 types: pitting, crevice corrosion, and filiform corrosion. Pitting is creating smalls hole in the metal (Bell, 2017). Crevice corrosion occurs in stagnant locations (Bell, 2017). Filiform corrosion happens when water gets under a coating (Bell, 2017). Galvanic corrosion is when two different