ART
BEAUTY & WELLNESS
CRAFT
CULTURE & HISTORY
ENTERTAINMENT
ENVIRONMENT
FOOD & DRINKS
REVERSE ENGINEERING
SCIENCES
SPORTS
TECHNOLOGY
WEARABLES
Metal Oxide Varistor: Zinc Oxide with 0.2 % Bismuth Oxide, Sintered Disc (Masuyama 1972)
A non-linear resistor: the current through it rises far faster than the voltage across it. Masuyama, Matsuoka and Nishi made one from zinc oxide with a little bismuth oxide: pressed into a disc, sintered, lapped, and given metal electrodes. With 0.2 mole % bismuth oxide, sintered at 1000 °C and lapped to 1 mm, the disc measured a C-value of 43 at 1 mA and a nonlinearity exponent n of 4.3.
Source: T. Masuyama, M. Matsuoka and T. Nishi (Matsushita), US 3,663,458 (1972), Example 1. Unknown: how the aluminium is sprayed on and what the silver paint is. The patent calls both well known, so they are linked to unknown heads. The 10 g batch is our arithmetic. Picture: the patent's drawing.
Advanced
1 day
Instructions
1
1
Weigh 99.8 ZnO to 0.2 Bi2O3 and wet-mill 5 hours
Weigh 99.8 ZnO to 0.2 Bi2O3 and wet-mill 5 hours
Mix zinc oxide and bismuth oxide 99.8 : 0.2 by moles. Ours, for 10 g: 9.887 g zinc oxide and 0.113 g bismuth oxide (our arithmetic). Mill wet for 5 hours, then dry. Unknown: the milling liquid.
Materials for this step:
Zinc Oxide Powder9.887 g
Bismuth Oxide0.113 gTools needed:
Balance Scale
Iron Ball Mill
Drying Oven2
2
Press discs 13 mm by 2.5 mm
Press discs 13 mm by 2.5 mm
Press the powder in a mould into discs 13 mm across and 2.5 mm thick at 340 kg/cm².
Tools needed:
Hydraulic Press
Disc Pressing Die
Vernier Caliper3
3
Sinter 1 hour at 1000 °C and furnace-cool
Sinter 1 hour at 1000 °C and furnace-cool
Sinter the discs in air for 1 hour at 1000 °C, then let them cool in the furnace to room temperature (about 15-30 °C). Above 1200 °C the disc loses its nonlinearity.
Tools needed:
Muffle Furnace4
4
Lap both faces to 1.0 mm
Lap both faces to 1.0 mm
Lap both faces with 600-mesh silicon carbide until the disc is 1.0 mm thick.
Tools needed:
Silicon Carbide GritVernier Caliper5
5
Spray aluminium electrodes and attach leads
Spray aluminium electrodes and attach leads
Spray a metallised film of aluminium on both faces. Attach a lead wire to each with conductive silver paint. Unknown: the spraying method and the paint.
Materials for this step:
Aluminium Ingot1 as required
Silver Conductive Paint1 as required
Copper Wire2 piecesTools needed:
Unknown Metal Spraying MethodVernier CaliperMaterials
5- 9.887 gPlaceholder
- 0.113 gPlaceholder
- 1 as requiredPlaceholder
- 1 as requiredPlaceholder
- 2 piecesPlaceholder
Tools Required
9- Placeholder
- Placeholder
- Placeholder
- Placeholder
- Placeholder
- Placeholder
- Placeholder
- Placeholder
- Placeholder
This blueprint makes
Related Blueprints
These blueprints share knowledge with this one — techniques, materials, or principles that connect them in the learning graph.
CC0 Public Domain
This blueprint is released under CC0. You are free to copy, modify, distribute, and use this work for any purpose, without asking permission.
Support the Maker by purchasing products through their Blueprint where they earn a Maker Commission set by Vendors, or create a new iteration of this Blueprint and include it as a connection in your own Blueprint to share revenue.