Ceramic igniters heat up much faster and hotter than their metal sheathed counterparts, providing greater reliability for your heating system and helping ensure consistent lighting of burners and performance.
The Washburn patent describes a 220 V igniter made up of 76v/o AlN, 9v/o SiC and 15v/o MoSi2. However, this composition displays unsuitably slow speed at 85% of its rated voltage.
Many conventional igniters utilize ceramic materials that become hot when electrified with an electrical current, providing ignition for heating systems. To function safely and without short circuiting or fire risks, these robust materials must also withstand high voltages without shattering under pressure.
Washburn's ceramic formulation (which includes AlN, MoSi2, SiC, and aluminum oxynitride) has been found unsuitable for high voltage performance due to the relatively thin hot zone cross section it offers.
As a result, it has been determined that when designing hairpin-style igniters with MoSi2 fractions greater than or equal to 6% and single leg lengths under approximately 1.2 inches, their temperature increase between 85%-110% of rated voltage is too extreme for stable operation. By comparison, using compositions with moderate NTCR allows for gradual temperature rise across ceramic.
FKK Corporation's ceramic igniters are ideal for gas phase fuels, quickly lighting pellets, wood chips, coal bricks and straw. Furthermore, these efficient igniters consume significantly less energy than standard metal sheathed products while remaining exceptionally durable.
When ceramic materials are electrified via wire leads, their internal atomic bonds expand as they absorb electrical energy and as the temperature of the material rises it also increases as its specific heat grows; ceramic materials have an even higher specific heat than steel in terms of specific heat output.
The Washburn patent describes a 220V igniter composed of 50V/o AlN, 42.2V/o SiC and 7.8V/o MoSi2 ceramic. Unfortunately, this composition limits how quickly this ceramic rises to its desired temperature; additionally it lacks the flexure strength required for demanding applications and falls below UL requirements for specific heat capacity; its moderate NTCR allows it to operate over a wide range of voltages with ease.
Silicon nitride ceramic heating elements heat up faster than metal sheathed igniters for quicker ignition and efficient heat production. Furthermore, their greater resilience against wear ensures long-term performance over their lifespan.
After attaching leads to the conductive portions of a preferred igniter and applying voltage, it was observed that it showed consistent heating performance, reaching its design temperature in about four seconds compared to conventional igniters which display unpredictable and unstable behavior as their operating voltage increases.
Washburn patent's 120V igniter features two legs connected by an electrical bridge, each featuring between 1-10 vol/o of densification aid such as yttria, magnesia or calcia for densification purposes. Each leg's middle portion also contains an electrically insulating composition to prevent the legs from touching one another; this creates a slot between them which enables this ceramic igniter to operate more reliably in high voltage applications than conventional igniters without supports.
Ceramic igniters are more resilient than their metal-sheathed counterparts and capable of maintaining an accurate temperature for an extended period. This makes ceramics particularly useful in wood pellet and biomass burners which require high temperatures in order to ignite fuel properly.
Igniters made from alumina and silicon nitride are safer than their metal counterparts as they don't contain lead, cadmium, mercury or chromium - all substances known to be toxic. Furthermore, their resistance to high voltages used during ignition processes makes them more durable than traditional igniters.
An inventive ceramic igniter includes both a support and hot zone, the latter of which should consist of at least 90% weight insulating material ceramic support material and at least 50 weight percent aluminum nitride, 10 weight percent molybdenum disilicide and 25 weight percent silicon carbide that can be sintered to form a densified laminate. Washburn taught that composition plays a far more crucial role than cross section when producing desired high voltage characteristics.