PTC Ceramic OCP (Low-resistivity grade)
Grade
Pick for resettable overcurrent protection, CRT degaussing and compressor motor start, where very low room-temperature resistivity and high surge-current capability matter more than heat output.
Values for the OCP condition
Other PTC Ceramic tempers and conditions
PTC Ceramic is listed in 4 conditions; see the grade overview at PTC Ceramic.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Sr-substituted low Curie grade | Choose the Sr-substituted body, whose Curie point drops to 30–90 °C, for low-temperature self-regulated heating such as warming pads and battery heaters, and for level or air-speed sensing. | — | 28 | 0 | 470 HV | 4 W/m·K |
HEATERDefault Heater grade | Use for self-regulating heating elements — constant-temperature plates, fan heaters, automotive heaters — with Curie points of 120–280 °C, medium room-temperature resistivity and AC 220 V withstand. | — | 30 | 0 | 500 HV | 4 W/m·K |
OCPThis page Low-resistivity grade | Pick for resettable overcurrent protection, CRT degaussing and compressor motor start, where very low room-temperature resistivity and high surge-current capability matter more than heat output. | — | 30 | 0 | 510 HV | 4 W/m·K |
High-resistivity sensor grade | Use where current must stay small: resistivity above 10 kΩ·cm and a large resistance jump suit temperature-limiting switches, overheat protection and heat-dissipation flow or level probes. | — | 30 | 0 | 500 HV | 4 W/m·K |
What is PTC Ceramic OCP?
PTC Ceramic OCP is PTC Ceramic in the OCP grade — pick for resettable overcurrent protection, CRT degaussing and compressor motor start, where very low room-temperature resistivity and high surge-current capability matter more than heat output. PTC Ceramic OCP has a tensile strength of 30 MPa (4.35 ksi), weaker than 77% of ceramic grades. Elongation at break is 0% and the elastic modulus is 112 GPa (16.2 Msi). PTC Ceramic OCP has a density of 5.65 g/cm³ (0.204 lb/in³), heavier than 57% of ceramic grades. It melts at 1,620°C (2,948 °F). HEATER is the default condition FabDigit quotes; OCP is available on request or by drawing note.
Advantages
- Low embodied carbon — 5 kg CO₂/kg, better than 76% of ceramic grades
Limitations
- Limited service temperature — 150°C (302 °F), worse than 90% of ceramic grades
- Hard to polish — 45/100, worse than 88% of ceramic grades
- Low fracture toughness — 1 MPa·√m (0.91 ksi·√in), worse than 84% of ceramic grades
PTC Ceramic OCP properties
Typical room-temperature values for PTC Ceramic OCP; 15 are specific to this condition. Other listed values are PTC Ceramic reference data and may not represent this condition. Bars are the position among ceramic grades.
Physical3
PTC Ceramic OCP has a density of 5.65 g/cm³ (0.204 lb/in³), heavier than 57% of ceramic grades. It melts at 1,620°C (2,948 °F).
Mechanical12
PTC Ceramic OCP has a tensile strength of 30 MPa (4.35 ksi), weaker than 77% of ceramic grades. Elongation at break is 0% and the elastic modulus is 112 GPa (16.2 Msi).
Thermal5
PTC Ceramic OCP is rated for continuous service to 150°C (302 °F). It conducts heat at 4.2 W/m·K (2.43 BTU/hr·ft·°F), worse than 65% of ceramic grades. Thermal expansion is 9.5 µm/m·K (5.28 µin/in·°F).
Electrical3
PTC Ceramic OCP is an electrical insulator with a dielectric strength of 1.5 kV/mm (38.1 V/mil) and a resistivity of 0.1 Ω·m.
Chemical & Environmental2
Corrosion resistance is very good (70/100), worse than 59% of ceramic grades.
Sustainability3
Producing a kilogram of PTC Ceramic OCP takes about 55 MJ of energy and emits 5 kg of CO₂ — less than 78% of ceramic grades. Typical recycled content is 0%.
Manufacturability3
PTC Ceramic OCP's machinability is not recommended (5/100, worse than 59% of ceramic grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with PTC Ceramic OCP
Is PTC Ceramic easy to machine?
After sintering, only diamond grinding, ultrasonic machining or laser cutting is practical. Do the shaping in the green state by dry pressing or tape casting plus blanking, and allow about 15–20 % sintering shrinkage in the green dimensions.
Can PTC Ceramic be welded?
Not weldable. Contact is made by firing silver paste or Al–Ni ohmic electrodes and then soft-soldering or using spring-clip pressure contacts; keep solder temperature and dwell controlled so electrode diffusion does not degrade contact resistance.
Can PTC Ceramic be formed, bent or molded?
Spray-granulated powder is dry-pressed into discs or rings, or tape-cast into thin sheets; sinter at 1280–1400 °C in air or an oxygen-rich atmosphere and cool slowly to develop the grain-boundary oxygen adsorption layer. Atmosphere and cooling rate determine the resistance jump ratio.
What surface finishes work on PTC Ceramic?
Grind the end faces flat, then screen-print the ohmic electrodes (Al/Ni-Ag or ohmic Ag). Side faces can carry an insulating glaze or epoxy encapsulation to resist humidity and surface tracking.
PTC Ceramic chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| SrTiO3lowers Curie point (higher in low-temperature types) | 0 – 6 | 2 |
| PbTiO3raises Curie point (>150 °C legacy formulas, RoHS-restricted) | 0 – 5 | 0 |
| Y2O3donor dopant, semiconducting grains (or La2O3/Sb2O3/Nb2O5) | 0.05 – 0.4 | 0.2 |
| MnO2acceptor; forms grain-boundary states, raises resistance jump | 0.01 – 0.05 | 0.02 |
| SiO2sintering aid / liquid phase | 0.3 – 2 | 1 |
| TiO2excess Ti, controls grain size | 0.2 – 2 | 0.8 |
| Al2O3+CaO+grain-boundary modification and sintering aids | 0 – 1.5 | 0.5 |
| BaTiO3matrix; slight Ti excess aids liquid-phase sintering | ≥ 92 (balance) | — |
PTC Ceramic OCP — frequently asked
What is PTC Ceramic OCP used for?
PTC Ceramic OCP is typically used for self-regulating heaters, motor start devices, overcurrent protection and degaussing circuits. In short: self-regulating heater ceramic; resettable overcurrent element; sharp Curie-point resistance jump.
What is the tensile strength of PTC Ceramic OCP?
PTC Ceramic OCP has a typical tensile strength of 30 MPa (4.35 ksi) — weaker than 77% of ceramic grades. Strength varies by condition: see the 4 listed tempers.
Is PTC Ceramic OCP easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 59% of ceramic grades). After sintering, only diamond grinding, ultrasonic machining or laser cutting is practical. Do the shaping in the green state by dry pressing or tape casting plus blanking, and allow about 15–20 % sintering shrinkage in the green dimensions.
Can PTC Ceramic OCP be welded?
Not weldable. Contact is made by firing silver paste or Al–Ni ohmic electrodes and then soft-soldering or using spring-clip pressure contacts; keep solder temperature and dwell controlled so electrode diffusion does not degrade contact resistance.
What surface finishes work on PTC Ceramic OCP?
Grind the end faces flat, then screen-print the ohmic electrodes (Al/Ni-Ag or ohmic Ag). Side faces can carry an insulating glaze or epoxy encapsulation to resist humidity and surface tracking.
Can PTC Ceramic OCP be formed, bent or molded?
Spray-granulated powder is dry-pressed into discs or rings, or tape-cast into thin sheets; sinter at 1280–1400 °C in air or an oxygen-rich atmosphere and cool slowly to develop the grain-boundary oxygen adsorption layer. Atmosphere and cooling rate determine the resistance jump ratio.
What is the maximum service temperature of PTC Ceramic OCP?
PTC Ceramic OCP is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASM Engineered Materials Handbook Vol.4 — Ceramics and Glasses — ASM International (1991)
- Electroceramics: Materials, Properties, Applications (Moulson & Herbert) — Wiley (2003)
- GB/T 6663 / IEC 60738-1 (PTC thermistors — surge suppression / heating) — IEC / SAC (2019)
- PTC heating element & thermistor disc datasheets ( PTC /Vishay/TDK ) — various (2024)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.