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    Process for preparing a PTC thermistor
    3.
    发明授权
    Process for preparing a PTC thermistor 失效
    制备PTC热敏电阻的工艺

    公开(公告)号：US4981633A

    公开(公告)日：1991-01-01

    申请号：US188306

    申请日：1988-04-29

    申请人： Aldo B. Alles ,  Vasantha R. W. Amarakoon ,  Vernon L. Burdick

    发明人： Aldo B. Alles ,  Vasantha R. W. Amarakoon ,  Vernon L. Burdick

    IPC分类号： C04B35/468 ,  C04B35/495 ,  H01C17/30

    CPC分类号： H01C17/30 ,  C04B35/4682 ,  C04B35/495

    摘要： A process for preparing a positive temperature coefficient thermistor is disclosed. This thermistor is comprised of at least about 60 weight percent of undoped, crystalline, ferroelectric material, and it has a room-temperature resistivity of less than 5,000 ohm-centimeters, an undegraded resistivity of at least about 1,000,000 ohm-centimeters, a degraded resistivity of at least about 900,000 ohm-centimeters, a ratio between its undegraded resistivity and its room-temperature resistivity of at least about 1,000, and a ratio between its undegraded resistivity and its degraded resistivity not exceeding 2.0.The process of this invention is comprised of the steps of sequentially: (1) providing a powder composition comprised of at least about 60 weight percent of undoped, crystalline, ferroelectric material; (2) fabricating the powder composition into a shaped powder compact; (3) sintering said powder compact by subjecting it to a temperature of from about 1150 to about 1450 degrees centigrade for at least about 1 hour, thereby forming a consolidated, sintered body; (4) reducing said sintered body by subjecting it to a temperature of from about 700 to about 1,400 degrees centigrade for at least about 30 minutes while maintaining said sintered body under a reducing atmosphere comprised of hydrogen; and (5) halogenating said reduced, sintered body by subjecting it to a source of halogen while maintaining it in a closed container at a temperature of from about 700 to about 1200 degrees centigrade for at least about 5 minutes.

    摘要翻译： 公开了一种制备正温度系数热敏电阻的方法。 该热敏电阻由至少约60重量％的未掺杂，结晶的铁电材料组成，并且其具有小于5,000欧姆厘米的室温电阻率，至少约1,000,000欧姆厘米的未降解电阻率，劣化的电阻率 至少约900,000欧姆厘米，其未降解的电阻率与其室温电阻率之比至少约为1,000，其未降解的电阻率与其劣化的电阻率之比不超过2.0。 本发明的方法包括以下步骤：（1）提供由至少约60重量％的未掺杂的结晶的铁电材料组成的粉末组合物; （2）将粉末组合物制成成形粉末压块; （3）通过使其达到约1150至约1450摄氏度的温度至少约1小时来烧结所述粉末压块，从而形成固结的烧结体; （4）在将所述烧结体保持在由氢组成的还原气氛下，使所述烧结体经受约700至约1400摄氏度的温度至少约30分钟来还原所述烧结体; 和（5）通过使所述还原的烧结体在约700至约1200摄氏度的温度下将其保持在密闭的容器中至少约5分钟，将其经卤素源卤化。