НовостиNews
-
ПоискSearch
-
ТекстыTexts
-
ФотоPhotos
-
КартыMaps
-
СнаряжениеEquipment
-
LTLT
Resistance measurement (DC): Current (1A) goes from Tenma power supply to the sample and measured by Keythley 2000 multimeter. Voltage on the sample is measured by Keythley 2182A nanovoltmeter (CH2 does not work?!). Noise in this measurement is about $0.1\,\mu\Omega$, but there is an additional current-independent DC voltage slowly drifting with time. To exclude it and to reduce noise, each measurement is repeated about 100 times, the current direction is switched in the middle. Value of resistance (V/I) is fitted by smooth functions of time (1st- or 2nd-order polynoms) before and after the switch. From this fit we obtained resistance in the switch point and value of uncertainty in the measurement.
| Sample | Measurements,$\,\mu\Omega$ | RRR | R_mat,$\,10^{-9}\Omega\cdot m$ |
|---|---|---|---|
| #1. Silver wire, D = 1mm, L = 62 mm, 99.99%.
Goodfellow AG005160/45, temper:annealed. | $300K: 1370.42 \pm 0.04077$ $ 77K: 300.265 \pm 0.01815$ $4.2K: 58.3522 \pm 0.01161$ | $23.5$ | $17.3$ |
| #2. Silver wire, D = 1mm, L = 58 mm, 99.99%.
Goodfellow AG005160/45, temper:annealed. Annealed at 800C for 18h in 3.8e-2 mbar of air. | $300K: 1266.02 \pm 0.04493$ $4.2K: 2.79873 \pm 0.04086$ | $452.4$ | $17.1$ |
| #11. Silver wire, D = 1mm, L = 36 mm, 99.99%.
Goodfellow AG005160/45, temper:annealed. Annealed by gas torch. | $300K: 776.393 \pm 0.00355$ $4.2K: 5.13234 \pm 0.00347$ | $151.3$ | $16.9$ |
| #12. Silver wire, D = 1mm, L = 18 mm, 99.99%.
Goodfellow AG005160/45, temper:annealed. Annealed by gas torch (same as previous). | $300K: 423.818 \pm 0.00417$ $4.2K: 4.39952 \pm 0.00510$ | $96.3$ | $18.5$ |
| #8. Copper tube Dout = 0.50 mm, Din = 0.22 mm, L = 78 mm,
Goodfellow CU007100 99.9%, temper: as drawn | $300K: 10522.2 \pm 0.196$ $4.2K: 1442.13 \pm 0.006178$ | $7.30$ | $21.4$ |
| #18. Same sample (#8), L=85mm.
Annealed at 900C for 24h in 3.8e-2mbar of air | $300K: 9987.93 \pm 0.027$ $4.2K: 19.1186 \pm 0.0056$ | $522.4$ | |
| #14. 1mm copper sheet from stores, 1mm-wide stripe, L=78mm(?) | $300K: 1882.64 \pm 0.01372$ $4.2K: 311.084 \pm 0.006669$ | $6.05$ | $24.1$ |
| #19. Same sample (#14), L=88mm.
Annealed at 900C for 24h in 3.8e-2mbar of air. | $300K: 1644.17 \pm 0.0187$ $4.2K: 21.8235 \pm 0.0054$ | $75.3$ | |
| #15. 1mm OFE copper sheet, 1mm-wide stripe, L = 80 mm,
from http://sdnonferrous.co.uk, bought 3.11.2020 | $300K: 2756.41 \pm 0.008437$ $4.2K: 40.0723 \pm 0.003365$ | $68.8$ | $34.5$ |
| #20. Same sample (#15). L=80mm.
Annealed at 900C for 24h in 3.8e-2mbar of air. | $300K: 2282.98 \pm 0.01182$ $4.2K: 3.02137 \pm 0.0048 $ | $755.6$ | |
| #21. Same sample (#20). L=80mm.
Hardened my making a coil with D=3mm. | $300K: 2498.51 \pm 0.138 $ $4.2K: 12.4384 \pm 0.0041 $ | $200.9$ | |
| #16. unknown 0.5mm copper sheet from metal storage, 1mm-wide stripe, L = 66 | $300K: 10767.1 \pm 0.1074$ $4.2K: 341.62 \pm 0.01292$ | $31.5$ | $81.6$ |
| #21. Same sample (#16).
Annealed at 900C for 24h in 3.8e-2mbar of air. | $300K: 3291.52 \pm 0.01489 $ $4.2K: 2.83093 \pm 0.00345$ | $1162.7$ | |
| #17: CuNi tube, OD=1mm, ID=0.8mm, L=77mm,
Goodfellow CU137200/1, temper: hard | $300K: 122991 \pm 1.787$ $4K: 117581 \pm 0.8609$ | $1.04$ | $451.6$ |
| Sample | Measurements,$\,\mu\Omega$ | RRR | |
|---|---|---|---|
| #3. Cut Sample #2, spot-weld pieces, L=56mm.
Spot welder parameters: power 4-4, timings 20:50:20:20. | $300K: 1251.26 \pm 0.0325$ $4.2K: 4.1314 \pm 0.00321$ | $303$ | 300K: 28.65, 4K: 1.42 |
| #4. Add second welding to sample #3, L=56mm. | $300K: 1130.32 \pm 0.06676$ $4.2K: 4.13379 \pm 0.00391$ | $273$ | |
| #5. Press sample #4 with 6t into stripe 2.0x0.4mm, L=58mm. | $300K: 1171.52 \pm 0.008044$ $4.2K: 15.4275 \pm 0.002551$ | $76$ | |
| #6. Al disk, spot-welded to annealed silver wire.
Large welding machine, Al has melted. L=54mm Lwires=39mm. | $300K: 950.618 \pm 0.005486$ $4.2K: 3.59688 \pm 0.004049$ | $264$ | |
| #7. Al disk, welding with slow machine. Lwires=49mm. | $300K: 1140.46 \pm 0.0438$ $4.2K: 5.14774 \pm 0.00224$ | $221$ | |
| #9. Al disk, U-shaped leads, Lwires=18mm. | $300K: 479.562 \pm 0.005449$ $4.2K: 4.85385 \pm 0.004053$ | 98 | |
| #10. Old heat switch (thick Al piece) | $4.2K: 3.24299 \pm 0.005152$ | ||
| #13. Testing heat switch, Al annealed by gas torch. Lwires=43mm | $300K: 799.498 \pm 0.02134$ $4.2K: 4.34862 \pm 0.005412$ | $183.7$ |
