Production method of needle-type heater

1. A production method of a needle-type heater, comprising steps of:

(1), preparing and mixing materials: weighing alumina powders of D50<0.8 μm, and adding into a ball mill; then adding a certain amount of milling balls, wherein a weight ratio of the alumina powders to the milling balls is 1:2; then adding a binder into the ball mill, wherein the binder accounts for 3-15% of a total weight of raw materials; and continuously milling until the alumina powders and the binder are uniformly mixed;

(2), pugging: taking out the mixed powders; adding a lubricant which accounts for 3-10% of the total weight of the raw materials; then adding water which accounts for 15-20% of the total weight of the raw materials; uniformly stirring until uniformly mixed; taking out stirred pug, and placing into a rough pug mill for rough pugging; repeatedly pugging for at least three times, and obtaining alumina pug;

(3), aging: wrapping the alumina pug by a plastic wrap; aging for at least 48 hours; and obtaining a 96% alumina flexible ceramic body;

(4), cutting the ceramic body: placing the 96% alumina flexible ceramic body on a mechanical punch for size punching; and, after punching, obtaining a required dimension of a heater substrate and a heater supporting seat;

(5), printing: in a dust-free environment, printing resistance slurry on the flexible ceramic body after punching, so as to form a heating element thereon; and printing an electrode which is connected to the heating element;

(6), wrapping: wrapping the flexible ceramic body with the printed heating element and electrode on an alumina ceramic rod;

(7), forming: after warm isostatic pressing by a warm isostatic pressing machine at a temperature near 95-100° C., forming into a needle-shaped ceramic body;

(8), modifying: punching a heating-type ceramic sleeve preform body obtained after forming by the punch, and forming a tapered cap; checking and modifying sizes thereof;

(9), pre-firing: heating the modified ceramic sleeve preform body in a rubber removal furnace from a room temperature to 500° C. with a speed of <5° C./min, wherein: the temperature is kept at 100° C., 200° C., 300° C. and 400° C. respectively for 30 minutes and kept at a highest rubber removal temperature of 500° C. for 120 minutes, so as to completely remove organics;

(10), firing: in a reducing atmosphere filled with hydrogen, firing with a temperature increased to 500° C. with a speed of 10° C./min and then to 1650° C. with a speed of <5° C./min, and forming a heating-type ceramic sleeve; wherein the temperature is kept at 700° C., 900° C., 1100° C. and 1300° C. respectively for 30 minutes and kept at a highest firing temperature of 1500° C. for 120 minutes;

(11), welding: welding a connecting wire at the electrode of the heating-type ceramic sleeve after firing; and

(12), tin dipping: processing the heating-type ceramic sleeve after welding with tin dipping at a welding point for 2-3 seconds.

2. The production method of the needle-type heater, as recited in claim 1 , wherein: the alumina powders are pure alumina powders or a combination of mixing the alumina powders with at least one member selected from a group consisting of aluminum nitride, vein quartz, sandstone, quartzite, quartz sand, flint, diatomaceous earth, mullite, cordierite, wollastonite, andalusite, limestone, quartz, kaolin, potassium oxide, sodium oxide, calcium oxide, magnesium oxide, ferric oxide and titanium oxide.

3. The production method of the needle-type heater, as recited in claim 1 , wherein: the lubricant consists of soybean oil and tung oil; the soybean oil accounts for 40% of a total weight of the lubricant and the tung oil accounts for 60% of the total weight.