潤滑脂的高溫性能

溫(wen)(wen)度(du)(du)對于(yu)潤(run)滑(hua)(hua)(hua)脂(zhi)的(de)流動(dong)性(xing)(xing)(xing)具有(you)很大影響,溫(wen)(wen)度(du)(du)升高(gao),潤(run)滑(hua)(hua)(hua)脂(zhi)變(bian)軟，使(shi)得潤(run)滑(hua)(hua)(hua)脂(zhi)附(fu)著性(xing)(xing)(xing)能(neng)降低而易于(yu)流失(shi)。另外,在較(jiao)高(gao)溫(wen)(wen)度(du)(du)條件(jian)下還(huan)易使(shi)潤(run)滑(hua)(hua)(hua)脂(zhi)的(de)蒸(zheng)(zheng)發(fa)損失(shi)增大,氧(yang)化變(bian)質與(yu)凝縮(suo)(suo)分油現(xian)象嚴重。潤(run)滑(hua)(hua)(hua)脂(zhi)失(shi)效的(de)主(zhu)要原(yuan)因,大多是由(you)于(yu)凝膠的(de)wei縮(suo)(suo)和(he)基礎油的(de)蒸(zheng)(zheng)發(fa)損關(guan)所致,即潤(run)滑(hua)(hua)(hua)脂(zhi)關(guan)效過程(cheng)的(de)快(kuai)慢與(yu)基使(shi)用溫(wen)(wen)度(du)(du)有(you)關(guan)。高(gao)溫(wen)(wen)性(xing)(xing)(xing)能(neng)好(hao)的(de)潤(run)滑(hua)(hua)(hua)脂(zhi)可以在較(jiao)高(gao)的(de)使(shi)用溫(wen)(wen)度(du)(du)下保持基附(fu)著性(xing)(xing)(xing)能(neng),其變(bian)質失(shi)效過程(cheng)也較(jiao)緩慢。潤(run)滑(hua)(hua)(hua)脂(zhi)的(de)高(gao)溫(wen)(wen)性(xing)(xing)(xing)能(neng)可用滴點、蒸(zheng)(zheng)發(fa)度(du)(du)和(he)軸承漏失(shi)量(liang)等指標(biao)進行評(ping)定。

潤(run)滑(hua)脂(zhi)(zhi)(zhi)的(de)滴點是指其在規定(ding)條(tiao)件(jian)下(xia)達到一(yi)定(ding)流動(dong)性(xing)時(shi)的(de)zui低溫(wen)度，以(yi)℃表(biao)示。滴點沒有絕對(dui)的(de)物理(li)意(yi)義,它的(de)數值因設備與加熱(re)速率不同而異。潤(run)滑(hua)脂(zhi)(zhi)(zhi)的(de)滴點主要取決于稠化(hua)劑的(de)種類與含(han)量,潤(run)滑(hua)脂(zhi)(zhi)(zhi)的(de)滴點可大致反映其使用(yong)溫(wen)度的(de)上限。顯然,潤(run)滑(hua)脂(zhi)(zhi)(zhi)達到滴點時(shi)其已(yi)喪失對(dui)金屬表(biao)面的(de)粘(zhan)附能力(li)。一(yi)般地說(shuo),潤(run)滑(hua)脂(zhi)(zhi)(zhi)應在滴點以(yi)下(xia)20℃一(yi)30℃或更低的(de)溫(wen)度條(tiao)件(jian)下(xia)使用(yong)。

潤滑(hua)(hua)脂(zhi)的滴點(dian)可按(an)GB/T4929— 85《潤滑(hua)(hua)脂(zhi)滴點(dian)測定(ding)(ding)(ding)法(fa)》進行測定(ding)(ding)(ding)。方法(fa)概要:將潤滑(hua)(hua)脂(zhi)裝入滴點(dian)計的脂(zhi)杯(bei)中(zhong),在規定(ding)(ding)(ding)的標準條件(jian)下,記錄潤滑(hua)(hua)脂(zhi)在試驗(yan)過程(cheng)中(zhong)達到規定(ding)(ding)(ding)流動性(xing)時(shi)的溫度。該標準與IsO/DP2176等效。GB/T3498—83是潤滑(hua)(hua)脂(zhi)寬溫度范圍滴點(dian)測定(ding)(ding)(ding)法(fa)。

潤(run)(run)(run)(run)(run)滑脂(zhi)(zhi)的(de)(de)蒸(zheng)發(fa)(fa)(fa)度是指(zhi)(zhi)在規定條件下蒸(zheng)發(fa)(fa)(fa)后,潤(run)(run)(run)(run)(run)滑脂(zhi)(zhi)的(de)(de)損失量所占的(de)(de)質量百分數。潤(run)(run)(run)(run)(run)滑脂(zhi)(zhi)的(de)(de)蒸(zheng)發(fa)(fa)(fa)度主要(yao)取決(jue)于所采用(yong)(yong)的(de)(de)基礎油(you)的(de)(de)種類、餾分組(zu)成和(he)分子量。高溫(wen)、寬溫(wen)度條件下使(shi)用(yong)(yong)的(de)(de)潤(run)(run)(run)(run)(run)滑脂(zhi)(zhi),其蒸(zheng)發(fa)(fa)(fa)度的(de)(de)測定尤為重要(yao),蒸(zheng)發(fa)(fa)(fa)度可以(yi)(yi)定性地表示潤(run)(run)(run)(run)(run)滑脂(zhi)(zhi)上限使(shi)用(yong)(yong)溫(wen)度。潤(run)(run)(run)(run)(run)滑脂(zhi)(zhi)基礎油(you)蒸(zheng)發(fa)(fa)(fa)損失,就會使(shi)潤(run)(run)(run)(run)(run)滑脂(zhi)(zhi)中的(de)(de)皂基稠(chou)化(hua)劑含量相對增(zeng)大,導致脂(zhi)(zhi)的(de)(de)稠(chou)度發(fa)(fa)(fa)生(sheng)變化(hua),使(shi)用(yong)(yong)中會造(zao)成內摩擦增(zeng)大,影(ying)響潤(run)(run)(run)(run)(run)滑脂(zhi)(zhi)的(de)(de)使(shi)用(yong)(yong)壽(shou)命。因而,蒸(zheng)發(fa)(fa)(fa)度指(zhi)(zhi)標可以(yi)(yi)從一定程(cheng)度上表明潤(run)(run)(run)(run)(run)滑脂(zhi)(zhi)的(de)(de)高溫(wen)使(shi)用(yong)(yong)性能。