臺灣博碩士論文加值系統

近年來隨著精密沖壓,塑膠射出成形等工業的高度發展,對於耐熱,高強
度及耐高溫腐蝕性 材料製程之元件的需求日益迫切,因而,對於超硬合金
材料之要求呈多元化.合金元素的添加及表面被覆陶瓷硬膜處理,均可有效
地提高碳化鎢系合金之機械性質.氮化鉻具有高硬度,高熔點,耐腐蝕性佳
等優點,將其濺鍍於碳化鎢合金基材上時,沉積時所須之基材溫度較低於其
他碳化物或氮化物被覆材,並顯示有較高的沉積速率,表面摩擦係數較小於
TiN,且有較佳的抗氧化及附著性. 本實驗為利用磁控濺射離子被覆法,在
不同成份之碳化鎢基材上被覆氮化鉻硬膜.在相同的製程條件下,對於不同
之基材進行氮化鉻鍍膜之結晶構造,顯微組織,被覆後之硬度及鍍膜與基材
界面性質之變化.此外,以XRD之sin2法對鍍層進行殘留應力分析,以期找出
殘留應力對微觀組織及被覆層附著力之影響. 實驗結果顯示:氮化鉻被覆
於不同成份之碳化鎢基材時,均會有相同之結晶結構,且鍍膜呈緻緻密的纖
細柱狀組織,但在鍍膜厚度上確有不同,在WC+Ni基材上之厚度最厚,而在
WC+6%Co基材之厚度最小.此外,由於鍍膜中存在之殘留應力值將使得被覆
後之硬度值有所提升,而此硬度值之提升量與鍍膜之厚度有關.附著性之刮
痕試驗結果顯示:鍍膜之結晶優選位向,鍍層厚度,基材硬度及其內應力值
均會影響臨界荷重,一般而言,較厚鍍膜及較低基材硬度,都將會增加鍍膜
與基材間之附著力,然而過高的殘留應力或存在有應力梯度時,都將會不利
於鍍膜之附著.

Recently, due to the highly developed techniques in precision
and injectionmolding, compoments made with high strength, high
temperature crossion resistance materials are in greater need
everday. Thus the properties ofsuperhard alloys are needed to be
improved in many ways. Alloy addition and/ordeposition of
ceramic hard coating can improve their mechanical properties at
elevated temperature: thereby greatly increase their lifetime.
Chromium nitridhas many fine properties such as high hardness,
high melting point and crossionresistance. When CrN is coated on
cemented tungsten carbides by the method ofmagnetron sputtering
ion plating, the temperature required for the substrste
isgrenerally lower than when the other carbides or nitrides are
used. the depositionrate is high, the surface friction
coefficient is smaller than TiN. In this study, four different
cemented tungsten carbides were used as substrateand coated with
chromium nitride film in a magnetron sputtering ion plating
system under the similar conditions. The structures and
mechanical properties of films, were studies by using XRD, SEM,
hardness tester and wear testingmachine. In addition, XRD sin2Ψ
method was used to evaluate the effects of residual stress in
the film. The results showed that the coated films on
different substrates havethe same crystal structure with dense
columnar grains. However, film thickness were different. WC+Ni
substrate is coated with thicker film and the film on WC+6%Co is
thinner. The hardness of all coated WC were improved due to the
presence ofcompressive stress inside the films. During the
scratch test, the thickness, residual stress, preferred
orientation of the film, and the substrate hardnessplay some
roles in determining the citical load ( Lc ). In general, the
experimental result shows that better adhesion was achieved by a
combination of relatively soft substrate with a thicker film
with moderate residual stress.However,when the residual stress /
stress gradient is too high the adhesion becomes poor.