Boundary friction(old)
In solid friction the friction acts between material zones that exhibit solid properties and are in direct contact. If the friction occurs between solid boundary layers with modified properties compared with the bulk material, e.g., between reaction layers, then this is boundary-layer friction. If the boundary layers on the contact surfaces each consist of a molecular film coming from a lubricant, then this is called boundary friction. In boundary friction, the lubricant’s hydrodynamic effect can be disregarded because the velocity is very low and/or only a very small quantity of lubricant, insufficient to fill the lubrication gap, is present.
(Springer Handbook of Mechanical Engineering, Grote, Antonsson (Eds.),part B, p302)
Boundary friction(new) [mechanics]
Boundary friction or boundary layer friction is defined as a frictional state in which the normal force (Fn) is no longer transmitted by hydrodynamic pressure, not even partially. The friction coefficient is very high
There is dry friction. The tooht flanks are only seperated by a boundary layer of chemical reaction products a few nanometers thick. Intended to prevent metal-to-metal contact.
(Automotive Transmissions: Fundamentals, Selection, Design and Application Author: Harald Naunheimer,Bernd Bertsche,Joachim Ryborz,Wolfgang Novak p.334)
-new definition is more clear and understandable
---------------------------------------------------------------------------------------------------------------------------------
Planishing(old)
Planishing is a kind of work refinement which, when carried to its ultimate state, can render a surface as fine as a mirror. After the raising operation, the work is begun by coarse hammer blows at the rate of about forty percent coverage. During this phase of the work,the most likely fitting stakes are sought out.
In these way the workpiece is not totally committed to stakes that may look right at the outset but later may not fit at all. When the project is important enough, it is fitting that the craftsman make new stakes to fit the needs of the job.
After the first planishing, the piece is annealed and left white, or matte from the pickling. This will help in seeing the new hammer marks better. This time the coverage is increased to sixty percent, not counting the previous forty percent marks. The transition areas from the to stake have to be overlapped very well, otherwise the typical transition welts will accur.
Initially, immediately after the raisinig state, the raising welts should be removed in the forty percent planishing phase. This is best done across the welts. In a round domical form, the planishing may be radially or concentrically oriented. In a cylindrical form, triangular of the planishing marks is employed. Triangulation is effective on other forms also, for planishing as well as to check the forms themselves.
(Heikki Seppä, Form emphasis for metalsmiths, Second Edition, page 33)
Planishing (new) [metal forming]
The object of planishing is to harden the metal hammered, and to close the coarse grain usually seen on unhammered shet metal, this causing the surface to become quite smooth and glossy and consequently rendering itmore capable of taking the brilliant polish usually associated with planished work. When metal is tinned before planishing, then , in addition to the improvements in the metal stated above, the tin is worked well into the pores of the planished metal, and consequently the tinned surface remains in good condition much longer than in the case with an article not planished. It is much to be regretted that this is not generally known.
(Metalworking: Tools, Materials, and Processes for the Handyman Author: Paul N. Hasluck p.162)
Planishing sheet metal requires great care and attention from the operator, besides considerable skill, which is only developed after practice. The art consists in hammering regularly over to the surface of a sheet metal until it has been completely covered by the hammer blows. The hammers used for this purpose are nearly flat and vary in weight from about 3lb to8. The anvils which the metal is hammered are also nearly flat. The surfaces of both hammer and anvil should be bright and after use should be carefully oiled to prevent any rust spots forming.
When planishing large work, it is good practice to commence by working straight across the center of the shoot and then form the line of hammer blows.
-new definition is more simple and is concerned more about topic
-----------------------------------------------------------------------------------------------------------------------
Photofabrication (old) - none
Photofabrication(new) [manufacturing]
Photofabrication is a general term for the working and shaping of materials such as metals and plastics to make components and devices using teclmiques of photography. ln outline. the basic technique involves coating the substrate material with a thin layer of photoresist, which , after the suitable exposure to a photomaster pattern and processing, forms a surface stencil that is resistant to an etchant or solvent for the substrate. Hence patterns such as printed circuits may be produced.
(Scientific Photography and Applied Imaging Author: Sidney F. Ray p.237)
SOFT LITHOGRAPHY(old) -none
SOFT LITHOGRAPHY(new) [nanotechnology]
A rather new approach to creating two-dimensional patterns on the nanoscale has recently arisen. This patterning technique is called soft lithography, and it relies on the use of various elastomeric stamps rather than rigid photomasks. The most common forms of soft lithography are called microcontact printing and replica molding. In each of this techniques a stamp or mold is created out of poly that has relief structures on its surface. In replica molding, the stamp is a two-dimensional surface posessing the nanoscale relief structures, ad it is used to make multiple copies of the pattern by pressing it repeatedly into moldable polymetric surfaces. 
With microcontacting printing, chemicals are applied to the raised structures on the surface of the stamp, and they are transferred to the surface being printed upon, much like an address stamp transfers ink to an envelope. The stamp can be a two-dimensinal surface with relief structures, or it can be a roller with relief structures, similar to a decorative paint roller used to paint a repetetive flower or ivy trim on a hause. Rolling this structure over a surface transfers the chemicals from the stamp to the surface.
(Modern Physical Organic Chemistry Author: Eric V. Anslyn,Dennis A. Dougherty)
--------------------------------------------------------------------------------------------------------------------------
benim 3 kelimemi açıklamışsın ama hoca bir kişiden en fazla iki kelime alabileceğinizi söyledi, fazla olan kelimeyi başka bir arkadaşınla paylaşabilirsin, tasarruf sende :)
ReplyDeletetamam perşembeye kadar halledeceğim
ReplyDelete