【正文】 ....................... 6 4 刀具涂層技術(shù)綜述 .................................................................................................... 7 化學(xué)氣相沉積涂層 .......................................................................................... 7 高溫化學(xué)氣相沉積涂層的優(yōu)點 .............................................................. 7 高溫化學(xué)氣相沉積涂層的缺點 .............................................................. 7 中溫化學(xué)氣相沉積涂層優(yōu)點 .................................................................. 7 物理氣相沉積涂層 .......................................................................................... 7 物理氣相沉積涂層步驟 ......................................................................... 8 物理氣相沉積涂層優(yōu)點 ......................................................................... 8 物理氣相沉積涂層缺陷 ......................................................................... 8 等離子體化學(xué)氣相沉積涂層 ............................................................................ 8 等離子體化學(xué)氣相沉積涂層優(yōu)點 ........................................................... 8 等離子體化 學(xué)氣相沉積涂層缺點 ........................................................... 8 溶膠 凝膠法 .................................................................................................. 9 5 刀具涂層改性意見 .................................................................................................... 9 6 結(jié)語 ......................................................................................................................... 9 參考 文獻 .................................................................................................................... 10 致謝 ............................................................................................................................ 11 刀具涂層技術(shù)理論研究 1 摘要 機械制造工業(yè)是制造業(yè)最重要的組成之一 ,它擔(dān)負著向國民經(jīng)濟的各個部門提供機械裝備的任務(wù)。本文應(yīng)用試驗的方法 ,通過不同涂層材料的刀具進行切削加工 ,在保證加工質(zhì)量的前提下 ,尋求切削加工的最佳參數(shù)。 粘結(jié)磨損 粘結(jié)是指刀具與工件材料接觸到原子間的距離 時所產(chǎn)生的結(jié)合現(xiàn)象。擴散磨損常常伴有接觸表面層中成分的分解 ,工件 材料和刀具材料成分之間的相互擴散。在此期間 ,由于對切削刀具涂層市場前 景看好 ,國內(nèi)共有七家大型工具廠從國外引進了大型 PVD涂層設(shè)備 (均以高速鋼 TiN涂層工藝為主 )。因此 ,涂層制備工 藝至關(guān)重要。 PVD涂層技術(shù)能制備氮化鈦、碳氮化鈦、鋁鈦氮化合物以及各種難熔金屬的碳化物和氮化物等涂層。溶膠 凝膠法鍍膜生產(chǎn)成本相對較低 ,制品均勻度高、純度高。 trust, 158 . 601, 15 S. Ct. 912, 39 L. Ed. 1108 [1895]). After many years of debate and promise, the sixteenth amendment to the Constitution was ratified in 1913, providing Congress with the power to lay and collect taxes on ine without apportionment among the states. The objectives of the ine tax were the equitable distribution of the tax burden and the raising of revenue. Since 1913 the . ine tax system has bee very plex. In 1913 the ine tax laws were contained in eighteen pages of legislation。 最后 ,我要感謝我的家人和朋友 ,是他們的關(guān)心 !鼓勵和資助 ,使得我順利完成了大學(xué)階段的學(xué)習(xí)任務(wù)。一般來說 ,大部分硬質(zhì)合金刀具均采用 CVD 涂層技術(shù) ,而價格昂貴不可重磨的高速鋼等鋼制刀具、精密鋒利的硬質(zhì)合金精加工刀片和形狀復(fù)雜的硬質(zhì)合金整體棒 狀刀具均采用 PVD涂層技術(shù)。其涂層工藝的主要發(fā)展階段及應(yīng)用領(lǐng)域。但兩者的單一涂層均很難滿足高速切削對刀具涂層的綜合要求 ,故往往制成多元復(fù)合涂層 ,配制成較理想的刀具涂層材料。這種新涂層與基體結(jié)合強度高 ,涂層 膜硬度接近 CBN,抗氧化性能好 ,抗剝離性強 ,而且可顯著改善刀具表面粗糙度 ,有效控制精密刀具的刃口形狀及精度 , 我國 CVD 技術(shù)的發(fā)展 我國從二十世紀(jì)七十年代初開始研究 CVD 涂層技術(shù) ,由于該項技術(shù)專用性較強 ,國內(nèi)從刀具涂層技術(shù)理論研究 6 事研究的單位并不多。性質(zhì)較脆的刀具材料 (如陶瓷刀具材料和硬質(zhì)合金刀具材料 )在大多數(shù)情況下都會產(chǎn)生這種現(xiàn)象。涂層方法及過程參數(shù)影響硬涂層的顯微 結(jié)構(gòu) ,反之 ,顯微結(jié)構(gòu) (如顆粒尺寸 !顆粒結(jié)構(gòu) !顆粒邊界和相邊界 )又影響硬涂層的力學(xué)性能和金屬切削性能。 我們從多弧離子鍍技術(shù)工藝的角度 ,對刀具涂層質(zhì)量的因素進行了研究 ,發(fā)現(xiàn)影響刀具涂層質(zhì)量的因素主要是刀具溫度、涂層組分、涂層厚度等 【 1】 。我國現(xiàn)代化建設(shè)的發(fā)展速度在很大程度上要取決于機械制造工業(yè)的發(fā)展水平 ,因此 ,從這個意義上說 ,機械制造工業(yè)的發(fā)展水平是關(guān)系全局的。目前 ,金剛石涂層刀具多選用鎢鉆類硬質(zhì)合金 (wcco)或氮化硅 (SiN)等陶瓷材料作基體。它是在足夠大的壓力和溫度作用下 ,產(chǎn)生塑性變形而發(fā)生所謂的冷焊現(xiàn)象 ,是摩擦面塑性變形所形成的表面原子間吸附力所造成的結(jié)果。研究解決這些磨損機理 ,歸根到底就是要研究切削過程中刀具的應(yīng)力分布和溫度分布情況 ,找出發(fā)生磨損的薄弱環(huán)節(jié) ,通過先進的表面工程技術(shù)阻止或減緩以上 磨損現(xiàn)象的發(fā)生 ,從而達到延長刀具壽命的目的。技術(shù)及設(shè)備的引進調(diào)動了國內(nèi) PVD技術(shù)的開發(fā)熱潮 ,許多科研單位和各大真空設(shè)備廠紛紛展開了大型離子鍍膜機的研制工作 ,并于九十年代初開發(fā)出多種 PVD涂層設(shè)備。常用的刀具涂層工藝一般分為化學(xué)氣相沉積 (CVD)、中溫化學(xué)氣相沉積 (MTCVD)、物理氣相沉積 (PVD)、離子輔助沉積技術(shù) ( IBAD)、等離子增強化學(xué)氣相沉積技術(shù) (PECVD)以及溶膠 凝膠法 (SolGelMethod)。 物理氣相沉積涂層優(yōu)點 1)涂層沉積溫度低 ,一般在 600e以下 ,對刀具材料的抗彎強度影響很??； 2)涂層內(nèi)部的應(yīng)力狀態(tài)是壓應(yīng)力 ,更適應(yīng)于硬質(zhì)合金精密復(fù)雜刀具的涂層； 3)對環(huán)境不造成污染 ,符合目前綠色工藝、綠色制造的發(fā)展動向 ； 4)隨著納米涂層的出現(xiàn) , PVD涂層刀具質(zhì)量顯著提高 ,不僅具有結(jié)合強度高、硬度高和抗氧化性能好等優(yōu)點 ,還能有效地控制精密刀具刃口形狀及精度。燒結(jié)方法比傳統(tǒng)方法低約 400600e,反應(yīng)易于控制 ,尤其易于控制涂層的化學(xué)反應(yīng)等。 the explanation of the tax reform act of 1986 was more than thirteen hundred pages long (Pub. L. 99514, Oct. 22, 1986, 100 Stat. 2085). Commerce Clearing House, a publisher of tax information, released a version of the Internal Revenue Code in the early 1990s that was four times thicker than its version in 1953. Changes to the tax laws often reflect the times. The flat tax of 1913 was later replaced with a graduated tax. After the United States entered world war i, the War Revenue Act of 1917 imposed a maximum tax rate for individuals of 67 percent, pared with a rate of 13 percent in 1916. In 1924 Secretary of the Treasury Andrew W. Mellon, speaking to Congress about the high level of taxation, stated, The present system is a failure. It was an emergency measure, adopted under the pressure of war necessity and not to be counted upon as a permanent part of our revenue structure…. The high rates put pressure on taxpayers to reduce their taxable ine, tend to destroy individual initiative and enterprise, and seriously impede the development of productive business…. Ways will always be found to avoid taxes so destructive in their nature, and the only way to save the situation is to put the taxes on a reasonable basis that will permit business to go on and industry to develop. Consequently, the Revenue Act of 1924 reduced the maximum individual tax rate to 43 percent (Revenue Acts, June 2, 1924, ch. 234, 43 Stat. 253). In 1926 the rate was further reduced to 25 percent. The Revenue Act of 1932 was the first tax law passed during the Great Depression (Revenue Acts, June 6, 1932, ch. 209, 47 Stat. 169). It increased the individual maximum rate from 25 to 63 percent, and reduced personal exemptions from $1,500 to $1,000 for single persons, and from $3,500 to $2,500 for married couples. The national industrial reco