Mehmet Can ÇAPAR 030070131 10th week definitions

1-Eyelets (technique elements)


There is no old answer


(new answer)

Eyelets or small grommets are very handy in the shop for joining materials together permanently. They are less bulky than nuts and bolts; they join materials too thin or too soft to be tapped; and unlike rivets they leave a smooth-edged hole suitable either for the passage of wires or for hanging the object up on a finishing nail.

Turn the tools from drill rod to the dimensions shown in the drawing, or else obtain a supply of eyelets and proportion your tools to suit. Hardening and tempering to a blue color is desirable, though if the tools are to be used infrequently they can be left soft. File flats on the shank of the anvil so it can be held in a vise. You can retain the plunger either by turning a wide, shallow groove or filing a flat in it, and driving a pin into the body to project inside but clear the recessed portion.

(Popular Science, Feb 1948, pg:206)

2-Vacuum evaporation (coating technique)

There is no old answer.

(new answer)

Vacuum deposition (or vacuum evaporation) is a PVD process in which the atoms or molecules from a thermal vaporization source reach the substrate without collisions with residual gas molecules in the deposition chamber. This type of PVD process requires a relatively good vacuum. Although sputtering and sputter deposition were reported in the
mid-l800s using oil-sealed piston pumps, vacuum evaporation had to await the better
vacuums provided by the Springer mercury-column vacuum pumps. In 1879, Edison used this type of pump to evacuate the first carbon-filament incandescent lamps and in 1887 Nahrwold performed the first vacuum evaporation. Vacuum deposition of metallic thin films was not common until the I920s. Optically transparent vacuum-deposited antireflection (AR) coatings were patented by Macula (Zeus Optical) in 1935. The subject of early vacuum evaporation was reviewed by Glang in 1970 and most review articles and book chapters on the subject since that time have drawn heavily on his work.

Vacuum deposition normally requires a vacuum of better than 10^-4 Torr in order to have a long mean free path between collisions. At this pressure there is still a large amount of concurrent impingement on the substrate by potentially undesirable residual gases that can contaminate the film (see Figure 3.2). If film contamination is a problem, a high (10^-7 Torr) or ultrahigh (< 10^-9  Torr) vacuum environment can be used to produce a film with the desire purity, depending on the deposition rate, reactivities of the residual gases and depositing species, and the tolerable impurity level in the deposit.

(Donald M. Mattox, Handbook of Physical Vapor Deposition (PVD) Processing, pg:195)