在使用過程中，大多數措美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，措美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。措美機械密封端(duan)面(mian)(mian)(mian)摩(mo)(mo)擦的(de)(de)工(gong)(gong)況一般分為：流體(ti)摩(mo)(mo)擦、混(hun)合(he)摩(mo)(mo)擦和邊(bian)界摩(mo)(mo)擦三類，但不能長時間干(gan)摩(mo)(mo)擦。干(gan)摩(mo)(mo)擦狀(zhuang)態時，兩(liang)端(duan)面(mian)(mian)(mian)間的(de)(de)固(gu)體(ti)表面(mian)(mian)(mian)微凸(tu)體(ti)將直接(jie)接(jie)觸而引起劇(ju)烈的(de)(de)磨(mo)損(sun)。磨(mo)損(sun)時一方面(mian)(mian)(mian)會(hui)使摩(mo)(mo)擦表面(mian)(mian)(mian)物質(zhi)喪(sang)失或遷移，導致(zhi)表面(mian)(mian)(mian)損(sun)壞(huai)；另(ling)一方面(mian)(mian)(mian)會(hui)產生大量(liang)的(de)(de)摩(mo)(mo)擦熱直至燒(shao)毀密封。在(zai)無(wu)流體(ti)介(jie)質(zhi)的(de)(de)工(gong)(gong)況下，如何減少磨(mo)損(sun)降低(di)摩(mo)(mo)擦熱，那就要依靠(kao)干(gan)磨(mo)密封了(le)。

　　干磨密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)屬于浮動(dong)密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)的(de)(de)一種，常用(yong)材質(zhi)為耐(nai)磨碳(tan)精，結構(gou)包(bao)括環(huan)(huan)(huan)(huan)(huan)(huan)行(xing)(xing)(xing)密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)腔體和環(huan)(huan)(huan)(huan)(huan)(huan)行(xing)(xing)(xing)軸(zhou)套(tao)(tao)，密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)腔體內(nei)有(you)環(huan)(huan)(huan)(huan)(huan)(huan)行(xing)(xing)(xing)槽，槽內(nei)至少裝(zhuang)有(you)二(er)個截(jie)面(mian)(mian)為矩形的(de)(de)環(huan)(huan)(huan)(huan)(huan)(huan)行(xing)(xing)(xing)石(shi)墨密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)環(huan)(huan)(huan)(huan)(huan)(huan)，石(shi)墨密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)環(huan)(huan)(huan)(huan)(huan)(huan)的(de)(de)內(nei)徑與環(huan)(huan)(huan)(huan)(huan)(huan)行(xing)(xing)(xing)軸(zhou)套(tao)(tao)之(zhi)間(jian)有(you)0.01-0.04的(de)(de)間(jian)隙，軸(zhou)套(tao)(tao)外表面(mian)(mian)涂有(you)耐(nai)磨涂層，涂層材料一般為三氧(yang)化二(er)鋁(lv)或三氧(yang)化二(er)鉻。干磨密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)有(you)時需要(yao)增(zeng)加(jia)隔離氣，通(tong)常使(shi)用(yong)氮氣，氮氣耗量能控制(zhi)在25-40。主要(yao)應(ying)用(yong)于密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)易燃(ran)有(you)毒介質(zhi)，由于操作(zuo)維(wei)修簡單，密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)性(xing)好(hao)，不需要(yao)復(fu)雜的(de)(de)潤(run)滑冷卻系(xi)統(tong)，可以干運行(xing)(xing)(xing)，得到廣泛的(de)(de)應(ying)用(yong)。干磨密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)包(bao)括有(you)外罩(zhao)及架設(she)(she)于外罩(zhao)上(shang)且可呈(cheng)相對旋轉及貼合(he)的(de)(de)動(dong)密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)環(huan)(huan)(huan)(huan)(huan)(huan)及靜(jing)(jing)密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)環(huan)(huan)(huan)(huan)(huan)(huan)，靜(jing)(jing)密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)環(huan)(huan)(huan)(huan)(huan)(huan)與外罩(zhao)固定連接，靜(jing)(jing)密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)環(huan)(huan)(huan)(huan)(huan)(huan)及動(dong)密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)環(huan)(huan)(huan)(huan)(huan)(huan)上(shang)分開設(she)(she)有(you)供旋轉軸(zhou)安裝(zhuang)的(de)(de)通(tong)孔，且動(dong)密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)環(huan)(huan)(huan)(huan)(huan)(huan)與靜(jing)(jing)密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)環(huan)(huan)(huan)(huan)(huan)(huan)貼合(he)的(de)(de)端面(mian)(mian)分別為動(dong)密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)面(mian)(mian)及靜(jing)(jing)密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)面(mian)(mian)，外罩(zhao)上(shang)設(she)(she)有(you)促使(shi)動(dong)密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)環(huan)(huan)(huan)(huan)(huan)(huan)與靜(jing)(jing)密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)環(huan)(huan)(huan)(huan)(huan)(huan)緊密(mi)(mi)(mi)(mi)(mi)(mi)貼合(he)的(de)(de)彈性(xing)抵壓件。除了要(yao)保持密(mi)(mi)(mi)(mi)(mi)(mi)封(feng)(feng)(feng)(feng)(feng)(feng)面(mian)(mian)平行(xing)(xing)(xing)之(zhi)外，主要(yao)是摩擦副的(de)(de)材料問題。

　　摩擦材料(liao)應(ying)具備(bei)下(xia)列條件(jian)：

　　(1)機械強度高，能(neng)耐壓(ya)和(he)耐壓(ya)力變形；

　　(2)具有耐(nai)干磨(mo)性(xing)，耐(nai)高載荷性(xing)，自(zi)潤滑性(xing)好；

　　(3)配(pei)對(dui)材料的磨(mo)合性(xing)好，無過(guo)大的磨(mo)損和(he)對(dui)偶腐蝕；

　　(4)耐(nai)磨性(xing)好，摩擦(ca)材料(liao)雖然是易損件，起到保護(hu)制動(dong)或傳動(dong)裝置(zhi)的作用(yong)，但要求(qiu)具有(you)一定的耐(nai)磨性(xing)，使用(yong)壽(shou)命盡量(liang)要長，刮傷、腐蝕(shi)和(he)粘(zhan)附(fu)對偶，都會造成制動(dong)或傳動(dong)的震動(dong)和(he)不穩定；

　　(5)導(dao)熱(re)性(xing)(xing)和(he)散熱(re)性(xing)(xing)好，導(dao)熱(re)性(xing)(xing)是傳導(dao)熱(re)量的能(neng)力(li)大小，即(ji)包括吸熱(re)，也包括散熱(re)，所以，導(dao)熱(re)性(xing)(xing)好的必然(ran)散熱(re)性(xing)(xing)也好；

　　(6)抗熱(re)裂(lie)性(xing)好，根本(ben)解決(jue)抗熱(re)裂(lie)性(xing)問題可能需(xu)要改變封孔(kong)方法(fa)；

　　(7)耐(nai)腐(fu)蝕性(xing)強(qiang)，一些有(you)色金屬合金能將良好的摩擦學(xue)特(te)性(xing)與(yu)有(you)些流(liu)體的耐(nai)腐(fu)蝕性(xing)結(jie)合；

　　(8)線(xian)膨脹系(xi)數(shu)小，熱膨脹會造成摩(mo)(mo)擦(ca)(ca)材料與摩(mo)(mo)擦(ca)(ca)對偶之間(jian)的間(jian)隙過小，發生拖(tuo)摩(mo)(mo)，損毀制動、傳動裝置。