在使用過程中，大多數膠州機械密封都屬于接觸式密封，其機理是靠動密封環與靜密封環的接觸端面在密封流體壓力和彈性元件壓緊力的作用下緊密貼合，并相對滑動而達到密封。工作時，膠州機械密封端面上同時發生摩擦、滑動與磨損等現象，摩擦是它的基本特征。膠州機械密封端面(mian)(mian)(mian)(mian)摩(mo)擦(ca)(ca)的(de)(de)工況一般分為(wei)：流體摩(mo)擦(ca)(ca)、混合摩(mo)擦(ca)(ca)和邊界摩(mo)擦(ca)(ca)三類(lei)，但不(bu)能長時間干摩(mo)擦(ca)(ca)。干摩(mo)擦(ca)(ca)狀態(tai)時，兩端面(mian)(mian)(mian)(mian)間的(de)(de)固(gu)體表(biao)(biao)面(mian)(mian)(mian)(mian)微凸體將直(zhi)接接觸而引起(qi)劇烈的(de)(de)磨(mo)(mo)損。磨(mo)(mo)損時一方面(mian)(mian)(mian)(mian)會使(shi)摩(mo)擦(ca)(ca)表(biao)(biao)面(mian)(mian)(mian)(mian)物質喪失(shi)或遷移，導致表(biao)(biao)面(mian)(mian)(mian)(mian)損壞；另一方面(mian)(mian)(mian)(mian)會產生大量的(de)(de)摩(mo)擦(ca)(ca)熱直(zhi)至燒毀密(mi)封(feng)。在無(wu)流體介質的(de)(de)工況下，如何減少(shao)磨(mo)(mo)損降低摩(mo)擦(ca)(ca)熱，那(nei)就要依(yi)靠干磨(mo)(mo)密(mi)封(feng)了。

　　干(gan)磨密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)屬(shu)于浮動(dong)(dong)密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)的(de)一種，常(chang)用材質(zhi)為耐磨碳精，結構包括環(huan)行(xing)(xing)密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)腔體和環(huan)行(xing)(xing)軸套，密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)腔體內有環(huan)行(xing)(xing)槽，槽內至少(shao)裝(zhuang)有二個(ge)截面(mian)(mian)(mian)為矩形的(de)環(huan)行(xing)(xing)石墨(mo)密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)環(huan)，石墨(mo)密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)環(huan)的(de)內徑與環(huan)行(xing)(xing)軸套之間(jian)有0.01-0.04的(de)間(jian)隙，軸套外(wai)(wai)(wai)表(biao)面(mian)(mian)(mian)涂有耐磨涂層(ceng)，涂層(ceng)材料(liao)一般為三(san)氧(yang)化(hua)二鋁或三(san)氧(yang)化(hua)二鉻。干(gan)磨密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)有時需(xu)要(yao)(yao)增加隔離氣(qi)(qi)，通常(chang)使(shi)用氮(dan)(dan)氣(qi)(qi)，氮(dan)(dan)氣(qi)(qi)耗量(liang)能(neng)控(kong)制在25-40。主(zhu)要(yao)(yao)應(ying)用于密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)易燃有毒(du)介質(zhi)，由于操作維修簡(jian)單，密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)性好，不需(xu)要(yao)(yao)復雜的(de)潤(run)滑冷(leng)卻系統，可以干(gan)運行(xing)(xing)，得到廣泛的(de)應(ying)用。干(gan)磨密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)包括有外(wai)(wai)(wai)罩(zhao)(zhao)(zhao)及(ji)架設于外(wai)(wai)(wai)罩(zhao)(zhao)(zhao)上(shang)且(qie)可呈相(xiang)對(dui)旋轉及(ji)貼(tie)合(he)的(de)動(dong)(dong)密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)環(huan)及(ji)靜(jing)(jing)(jing)密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)環(huan)，靜(jing)(jing)(jing)密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)環(huan)與外(wai)(wai)(wai)罩(zhao)(zhao)(zhao)固定連(lian)接，靜(jing)(jing)(jing)密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)環(huan)及(ji)動(dong)(dong)密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)環(huan)上(shang)分(fen)開設有供旋轉軸安裝(zhuang)的(de)通孔，且(qie)動(dong)(dong)密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)環(huan)與靜(jing)(jing)(jing)密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)環(huan)貼(tie)合(he)的(de)端面(mian)(mian)(mian)分(fen)別為動(dong)(dong)密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)面(mian)(mian)(mian)及(ji)靜(jing)(jing)(jing)密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)面(mian)(mian)(mian)，外(wai)(wai)(wai)罩(zhao)(zhao)(zhao)上(shang)設有促使(shi)動(dong)(dong)密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)環(huan)與靜(jing)(jing)(jing)密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)環(huan)緊密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)貼(tie)合(he)的(de)彈性抵(di)壓件。除了要(yao)(yao)保持密(mi)(mi)(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)面(mian)(mian)(mian)平行(xing)(xing)之外(wai)(wai)(wai)，主(zhu)要(yao)(yao)是摩擦副的(de)材料(liao)問題。

　　摩擦(ca)材料應具(ju)備下列條件：

　　(1)機械強度高(gao)，能耐(nai)壓和耐(nai)壓力變形；

　　(2)具有耐干磨性(xing)(xing)，耐高載荷性(xing)(xing)，自潤滑(hua)性(xing)(xing)好；

　　(3)配對(dui)材料(liao)的(de)磨合性(xing)好，無過大的(de)磨損和(he)對(dui)偶(ou)腐蝕；

　　(4)耐磨性好，摩擦材料雖然是(shi)易損(sun)件(jian)，起到保護制動或(huo)(huo)傳動裝置的作用(yong)，但要求具有一定(ding)的耐磨性，使(shi)用(yong)壽命盡(jin)量(liang)要長，刮傷、腐蝕和粘附(fu)對偶，都會造(zao)成制動或(huo)(huo)傳動的震動和不穩(wen)定(ding)；

　　(5)導(dao)熱(re)(re)性和散熱(re)(re)性好(hao)，導(dao)熱(re)(re)性是(shi)傳(chuan)導(dao)熱(re)(re)量的能力(li)大小，即包(bao)括(kuo)吸熱(re)(re)，也(ye)包(bao)括(kuo)散熱(re)(re)，所以，導(dao)熱(re)(re)性好(hao)的必然散熱(re)(re)性也(ye)好(hao)；

　　(6)抗熱(re)裂(lie)性好，根本(ben)解決抗熱(re)裂(lie)性問(wen)題(ti)可能需要改變封孔方法(fa)；

　　(7)耐腐蝕性強，一(yi)些(xie)(xie)有(you)色金(jin)屬合金(jin)能將良好的(de)摩擦學特性與有(you)些(xie)(xie)流體的(de)耐腐蝕性結(jie)合；

　　(8)線膨脹(zhang)系數小(xiao)，熱膨脹(zhang)會造成(cheng)摩(mo)擦(ca)材料與摩(mo)擦(ca)對偶之間的間隙過小(xiao)，發生拖(tuo)摩(mo)，損毀制動、傳動裝置。