UBUHANZI
UBWIZA N'UBUZIMA
UBUKORIKORI
UMUCO N'AMATEKA
IMYIDAGADURO
IBIDUKIKIJE
IBIRIBWA N'IBINYOBWA
UBWUBATSI BUSUBIRA INYUMA
UBUMENYI
SIPORO
IKORANABUHANGA
IBYAMBARWA
PTFE (Polytetrafluoroethylene)
On 6. April 1938 Roy Plunkett at DuPont opened the valve on a cylinder of tetrafluoroethylene gas, a candidate refrigerant, and nothing came out - though the cylinder still weighed full. Sawn open, it held a white waxy powder: the gas had polymerised by itself. The powder resisted every solvent and acid tried on it, did not melt like other plastics, and almost nothing would stick to it.
**US 2,230,654**, "Tetrafluoroethylene polymers", Plunkett, assigned to Kinetic Chemicals, granted 4. February 1941. Its first claim is two words: "Polymerized tetrafluoroethylene."
**Tetrafluoroethylene is explosive and is never handled outside a plant.** You build what the material is for: a hinged tilting ramp that measures the coefficient of friction of PTFE against steel, beside nylon, acrylic and steel itself.
Utangiye
3 hours
Amabwiriza
1
1
The rig
The rig
The whole rig: a 400 mm base, a hinged ramp with a steel strip on top, a prop under the raised end, and a faced sled.
2
2
Cut base and ramp
Cut base and ramp
From 18 mm plywood saw two boards 400 x 120 mm. Sand the edges.
Ibikoresho by'iyi ntambwe:
Urupapuro rw'ibiti byometse1 igiceIbikoresho bikenewe:
Umucumita w'Intoki
Umurongo w'Icyuma
Igifata gifite ishusho ya C3
3
Hinge them
Hinge them
Lay the boards end to end and fit the butt hinge across one short joint with 4 wood screws, pilot-drilled 2 mm. The ramp must lift from flat to 45° without rocking.
Ibikoresho by'iyi ntambwe:
Ifatanya ry'urugi1 igice
Imisumari y'ibiti4 ibiceIbikoresho bikenewe:
Icyuma Cyivumbura Kidafite Insinga
Ibikoresho by'ibivumbura mu gasanduku
Ikusanyirizo ry'ibitorezi4
4
Fit the steel counterface
Fit the steel counterface
Stick a 360 x 100 mm strip of mild steel sheet to the ramp's top face with double-sided tape. Wipe it with isopropyl alcohol - grease halves any reading.
Ibikoresho by'iyi ntambwe:
Urupapuro rw'icyuma cyoroshye1 igice
Utepe ufata impande zombi1 umuzingo
Alukoli ya isopropili 99 %10 mlIbikoresho bikenewe:
Amadarubindi Asobanutse yo Kwirinda5
5
Make four sleds
Make four sleds
Saw four 60 x 60 mm plywood blocks. Face one each with PTFE, nylon, acrylic and steel cut to 60 x 60 mm, fixed with double-sided tape. Clean every face with alcohol.
Ibikoresho by'iyi ntambwe:
Urupapuro rwa PTFE1 igice
Urupapuro rwa nayiloni (6/6)1 igice
Urupapuro rwa Akiriliki1 igiceUrupapuro rw'icyuma cyoroshye1 igiceUtepe ufata impande zombi1 umuzingoIbikoresho bikenewe:
Umucumita w'Intoki
Icyuma gikata cy'akazi6
6
Tilt until it goes
Tilt until it goes
Set a sled 100 mm from the top. Raise the ramp slowly, about 1° per second. Stop the instant it slides and read the angle finder on the ramp. Five tries per sled.
Ibikoresho bikenewe:
Igipima IngoroUmurongo w'Icyuma7
7
Load it
Load it
Repeat the PTFE sled with a weight taped on top. The angle should not change.
Ibikoresho bikenewe:
UburemereIgipima Ingoro8
8
Angles into friction
Angles into friction
Gupakira ikaye ya Jupyter…
9
9
History & Context
History & Context
**What the patent specifies:** the polymer of tetrafluoroethylene itself, a solid insoluble in ordinary solvents. **Modern build (derived):** machined PTFE sheet against clean mild steel on a tilting plane.
Its first large use was seals and gaskets for the Manhattan Project's uranium hexafluoride plant, a gas that attacked everything else. DuPont registered Teflon in 1945; non-stick pans followed in the 1950s, and stretched PTFE became Gore-Tex. Its limits: it creeps under steady load, wears quickly without fillers, cannot be glued without etching, and above about 260 °C in use it begins to give off harmful fumes.
Ibikoresho
9- 1 igiceUmwanya
- Ifatanya ry'urugi10% komisiyo1 igiceUmwanya
- 4 ibiceUmwanya
- Umwanya
- 1 umuzingoUmwanya
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- 1 igiceUmwanya
- 1 igiceUmwanya
- 1 igiceUmwanya
Ibikoresho bikenewe
10- Umwanya
- Umwanya
- Umwanya
- 1 vendor sell this, none ship to you yetUmwanya
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Dosiye z'igishushanyo
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