一个人看的www视频免费观看_三男三女换着曰_人妻无码久久中文字幕专区_无码人妻丰满熟妇区五十路

 　　表面電阻率測試儀的影響因素主要有測試電壓，測試時間，環境溫濕度和外界干擾這些，下面一一來看下具體的影響在哪里。

　　1.測試電壓(電場強(qiang)度(du))對表面電阻率測試儀的影響(xiang)

　　Ø介質(zhi)材(cai)料的(de)(de)(de)電(dian)(dian)(dian)阻(zu)(率)值(zhi)一般(ban)不(bu)能(neng)在(zai)很(hen)寬的(de)(de)(de)電(dian)(dian)(dian)壓(ya)范圍內保(bao)持(chi)不(bu)變，即歐姆定(ding)律(lv)對此并不(bu)適用。常溫條件下(xia)，在(zai)較(jiao)低(di)的(de)(de)(de)電(dian)(dian)(dian)壓(ya)范圍內，電(dian)(dian)(dian)導電(dian)(dian)(dian)流(liu)隨外(wai)(wai)加(jia)電(dian)(dian)(dian)壓(ya)的(de)(de)(de)增加(jia)而線性增加(jia)，材(cai)料的(de)(de)(de)電(dian)(dian)(dian)阻(zu)值(zhi)保(bao)持(chi)不(bu)變。超過一定(ding)電(dian)(dian)(dian)壓(ya)后，由于離(li)子(zi)化運動加(jia)劇，電(dian)(dian)(dian)導電(dian)(dian)(dian)流(liu)的(de)(de)(de)增加(jia)遠比(bi)測(ce)試電(dian)(dian)(dian)壓(ya)增加(jia)的(de)(de)(de)快(kuai)，材(cai)料呈現(xian)的(de)(de)(de)電(dian)(dian)(dian)阻(zu)值(zhi)迅(xun)速降(jiang)低(di)。由此可(ke)見，外(wai)(wai)加(jia)測(ce)試電(dian)(dian)(dian)壓(ya)越(yue)高，材(cai)料的(de)(de)(de)電(dian)(dian)(dian)阻(zu)值(zhi)越(yue)低(di)，以致在(zai)不(bu)同(tong)電(dian)(dian)(dian)壓(ya)下(xia)測(ce)試得到的(de)(de)(de)材(cai)料電(dian)(dian)(dian)阻(zu)值(zhi)可(ke)能(neng)有較(jiao)大的(de)(de)(de)差(cha)別。

　　Ø值得注意的(de)(de)(de)(de)是，導致材(cai)料(liao)電(dian)阻值變化的(de)(de)(de)(de)決定因素是測(ce)(ce)試(shi)(shi)(shi)時(shi)的(de)(de)(de)(de)電(dian)場強度，而不是測(ce)(ce)試(shi)(shi)(shi)電(dian)壓。對(dui)相同(tong)(tong)的(de)(de)(de)(de)測(ce)(ce)試(shi)(shi)(shi)電(dian)壓，若測(ce)(ce)試(shi)(shi)(shi)電(dian)極之間的(de)(de)(de)(de)距離不同(tong)(tong)，對(dui)材(cai)料(liao)電(dian)阻率的(de)(de)(de)(de)測(ce)(ce)試(shi)(shi)(shi)結果也(ye)將(jiang)不同(tong)(tong)，正負(fu)電(dian)極之間的(de)(de)(de)(de)距離越小，測(ce)(ce)試(shi)(shi)(shi)值也(ye)越小。

　　2.測(ce)試時間對表(biao)面電阻(zu)率測(ce)試儀(yi)的(de)影(ying)響

　　Ø用一(yi)定(ding)(ding)的(de)直流(liu)(liu)電(dian)(dian)(dian)壓(ya)(ya)對被測(ce)材(cai)料(liao)加(jia)壓(ya)(ya)時，被測(ce)材(cai)料(liao)上的(de)電(dian)(dian)(dian)流(liu)(liu)不是瞬時達(da)(da)到(dao)(dao)穩定(ding)(ding)值(zhi)的(de)，而是有一(yi)衰減(jian)過程。在(zai)(zai)加(jia)壓(ya)(ya)的(de)同時，流(liu)(liu)過較(jiao)(jiao)大的(de)充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)(liu)，接著是比(bi)較(jiao)(jiao)長時間緩慢減(jian)小的(de)吸收電(dian)(dian)(dian)流(liu)(liu)，zui后(hou)達(da)(da)到(dao)(dao)比(bi)較(jiao)(jiao)平(ping)穩的(de)電(dian)(dian)(dian)導(dao)電(dian)(dian)(dian)流(liu)(liu)。被測(ce)電(dian)(dian)(dian)阻(zu)值(zhi)越(yue)高，達(da)(da)到(dao)(dao)平(ping)衡的(de)時間則(ze)越(yue)長。因此，測(ce)量(liang)時為(wei)了正確讀取(qu)被測(ce)電(dian)(dian)(dian)阻(zu)值(zhi)，應在(zai)(zai)穩定(ding)(ding)后(hou)讀取(qu)數值(zhi)或取(qu)加(jia)壓(ya)(ya)1分鐘(zhong)后(hou)的(de)讀數值(zhi)。

　　Ø另外(wai)，高絕緣材(cai)料(liao)(liao)的(de)電(dian)(dian)阻(zu)(zu)值(zhi)(zhi)還與其帶(dai)電(dian)(dian)的(de)歷(li)史有關。為準確評價(jia)材(cai)料(liao)(liao)的(de)靜電(dian)(dian)性能，在對(dui)(dui)材(cai)料(liao)(liao)進(jin)行(xing)電(dian)(dian)阻(zu)(zu)(率)測試(shi)(shi)(shi)時，應(ying)(ying)首先對(dui)(dui)其進(jin)行(xing)消電(dian)(dian)處理，并靜置(zhi)一定的(de)時間(jian)，靜置(zhi)時間(jian)可取(qu)5分鐘(zhong)，然后(hou)，再(zai)按測量程序(xu)測試(shi)(shi)(shi)。一般而言，對(dui)(dui)一種材(cai)料(liao)(liao)的(de)測試(shi)(shi)(shi)，至少應(ying)(ying)隨機(ji)抽取(qu)3～5個試(shi)(shi)(shi)樣進(jin)行(xing)測試(shi)(shi)(shi)，以(yi)其平均值(zhi)(zhi)作為測試(shi)(shi)(shi)結果(guo)。

　　3.環境(jing)溫(wen)濕(shi)度(du)對表面電阻率(lv)測(ce)試儀的影響

　　Ø一(yi)般材(cai)料的電(dian)(dian)(dian)阻值隨環境(jing)(jing)溫濕度的升(sheng)高(gao)而(er)減小(xiao)。相(xiang)對(dui)而(er)言，表(biao)面電(dian)(dian)(dian)阻(率(lv))對(dui)環境(jing)(jing)濕度比較敏感，而(er)體電(dian)(dian)(dian)阻(率(lv))則(ze)對(dui)溫度較為敏感。濕度增加(jia)(jia)，表(biao)面泄漏增大，體電(dian)(dian)(dian)導電(dian)(dian)(dian)流(liu)(liu)也會增加(jia)(jia)。溫度升(sheng)高(gao)，載流(liu)(liu)子的運動速率(lv)加(jia)(jia)快，介質(zhi)材(cai)料的吸收電(dian)(dian)(dian)流(liu)(liu)和電(dian)(dian)(dian)導電(dian)(dian)(dian)流(liu)(liu)會相(xiang)應增加(jia)(jia)，據有(you)關(guan)資料報道，一(yi)般介質(zhi)在70C時的電(dian)(dian)(dian)阻值僅有(you)20C時的10%。因此，測(ce)量材(cai)料的電(dian)(dian)(dian)阻時，必須(xu)指明試樣與環境(jing)(jing)達到平衡的溫濕度。

　　4.外界干擾對表面電阻率測試儀的影響

　　Ø高(gao)絕(jue)緣材料加上直(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)壓后，通(tong)過試(shi)(shi)(shi)(shi)樣的(de)(de)(de)電(dian)(dian)(dian)(dian)流(liu)(liu)是很(hen)微(wei)小(xiao)的(de)(de)(de)，極易受到外(wai)界干擾(rao)(rao)的(de)(de)(de)影(ying)響，造(zao)成較大的(de)(de)(de)測試(shi)(shi)(shi)(shi)誤差。熱電(dian)(dian)(dian)(dian)勢(shi)(shi)、接觸電(dian)(dian)(dian)(dian)勢(shi)(shi)一般很(hen)小(xiao)，可(ke)(ke)以忽略;電(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)勢(shi)(shi)主要(yao)是潮濕試(shi)(shi)(shi)(shi)樣與不同金屬接觸產生的(de)(de)(de)，大約只有20mV，況(kuang)且在(zai)靜電(dian)(dian)(dian)(dian)測試(shi)(shi)(shi)(shi)中均(jun)要(yao)求相對濕度較低，在(zai)干燥(zao)環境中測試(shi)(shi)(shi)(shi)時(shi)，可(ke)(ke)以消除電(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)勢(shi)(shi)。因此，外(wai)界干擾(rao)(rao)主要(yao)是雜(za)散電(dian)(dian)(dian)(dian)流(liu)(liu)的(de)(de)(de)耦合或(huo)(huo)靜電(dian)(dian)(dian)(dian)感(gan)應產生的(de)(de)(de)電(dian)(dian)(dian)(dian)勢(shi)(shi)。在(zai)測試(shi)(shi)(shi)(shi)電(dian)(dian)(dian)(dian)流(liu)(liu)小(xiao)于(yu)10-10A或(huo)(huo)測量電(dian)(dian)(dian)(dian)阻超過1011歐姆(mu)時(shi);被測試(shi)(shi)(shi)(shi)樣、測試(shi)(shi)(shi)(shi)電(dian)(dian)(dian)(dian)極和(he)測試(shi)(shi)(shi)(shi)系(xi)統均(jun)應采取嚴格的(de)(de)(de)屏蔽措施，消除外(wai)界干擾(rao)(rao)帶來的(de)(de)(de)影(ying)響。