Silicon Steel
This steel was developed by the English metallurgist Robert Hadfield in 1900 and soon became the preferred core material for large transformers, motors and generators. The addition silicon to iron profoundly modifies the phase diagram as shown by figure.This means that such an ally may be recrystallized at any temperature without concern for phase change and single crystals of such an ally can be made by slow solidification from liquid or by recrystalization at ay desired temperature. (Introduction to magnetic materials, Bernard Dennis Cullity,Chad D. Graham)
Hydrohoning
A special form of grit blasting is hydrohoning in which the abrasive medium is sespended in a liquid which is then directed onto the surface in the form of a high-pressure jet. (Handbook of ceramic grinding and polishing, Ioan D. Marinescu, Hans Kurt Tönshoff, Ichiro Inasaki)
Rheocasting
Rheocasting is the casting semisolid slurries, which is conducted within the liquidus-solidus range of metallic alloy. This process uses molten ally as the starting material thus eliminating the demand of specially feedstock materilas. In comparison with conventiobnally cast parts, rheocast components the following advantages: Homogeneous distribution of microporsity, Less tendency of shrinkage pipe and crack formation, Less tendency of micro and macrosegragation, A fine and nondendritic grain structure.
Reverse Redrawing
When high drawing ratios are required, the process is decomposed into two or several steps, in order to increase the formability by preventing localisation of the deformation in the cup wall. Re-drawing processes are usually sorted out in two categories: direct and reverse re-drawing.The first one corresponds to a process in which the different punches are always in contact with the same blank side whereas during reverse re-drawing, the punch travel occurs in two opposite directions and the outside of the part during the first stage becomes the inside of the part in the second stage. The advantages of the reverse process are a more compact tooling, without new positioning of the part in-between the two stages, a better surface aspect than in the case of a direct process because the outside is in contact only once with the die radius and finally a smaller number of bending–unbending operations. (Experimental and numerical study of reverse re-drawing of anisotropic sheet metals S. Thuilliera,*, P.Y. Manacha, L.F. Menezesb, M.C. Oliveira)
Nibbling
Sheet metal cutting process in which a rapidly reciprocating punch slots sheets along desired path. (Academic Press dictionary of science and technology, Christopher G. Morris,Academic Press)
Microfabrication
As the name implies, microfabrication involves, all processes that make products on the submilimeter scale. Many traditional and nontradiotional processes are capable of doing so: Wires are drawn to a few micrometers in diameter; metal foils are rolled to a few microns in thickness. ( Introduction to manufacturing processes, John a. Schey)
Chemical Voper Depositon - CVD
Chemical vapor deposition (CVD) is a versatile process in which gas-phase molecules are decomposed to reactive species, leading to film or particle growth. CVD processes can be used to deposit a wide range of conducting, semiconducting, and insulating materials. (Chemical Vapor Deposition Based Synthesis of Carbon Nanotubes and Nanofibers Using a Template Method G. Che, B. B. Lakshmi, C. R. Martin, and E. R. Fisher, Rodney S. Ruoff)
Fluidity Index
Although none is accepted universally, several tests have been developed to quantify fluidity. One such test is shown in Fig.5, where the molten metal is made to flow along a channel at room temperature. Obviously this length is a function of the thermal properties of the metal and the mold, as well as the design of the channel. The fluidity index is the length of the solidified metal in the spiral passage. The greater the length of the solidified metal, the greater is its fluidity. (Umm Al-Qura University Lecture Notes of Casting, Chapter 2)
No comments:
Post a Comment