腐蚀与防护-ppt课件.ppt

1、Materials Corrosion and Protection1 Instructor:Dr. Jing MADepart. of Metallic Materials EngineeringOffice: A344 Material BuildingE-mail: Bilingual TeachingDemand of economic globalization.China Ministry of Education “Bilingual Teaching Course Reform Plan” , 2001To improve students learning and acqui

2、ring of make them competent for international communication in their specialty fields.Contents of the subject:Chapter 1 IntroductionChapter 2 Chapter 3 Chapter 4 Nature Corrosion Chapter 5 OxidationChapter 6 Corrosion Control(1)杨德钧，沈卓身, 金属腐蚀学. 冶金工业版(2) http:/ and corrosion controlBy R. Winston Revie

3、 很有用的网址：很有用的网址： http:/ Google搜索：MIT open course何业东，齐慧滨. 材料腐蚀与防护概论. 机械工业版 o 腐蚀源于拉丁文“corrdere”，意即“损坏”、“腐烂”lCorrosion can be defined as the degradation of a material due to a reaction with its environment. 材料与环境组分发生的物理的、化学和电化学作用而引起的变质和破坏，称之为腐蚀腐蚀。 lMaterials can be metals, polymers (plastics, rubbers, e

4、tc.), ceramics (concrete, brick, etc.) or composites mechanical mixtures of two or more materials with different properties. Questions: Questions:lMetals corrode because we use them in environments where they are chemically unstable. l most metals are commonly in the form of various chemical compoun

5、ds (ores).l Only copper and the precious metals (gold, silver, platinum, etc.) are found in nature in their metallic state.smelting, refining processescorrosionl All other metals are unstable and have a tendency to revert to their more stable mineral forms. l Some metals form protective ceramic film

6、s (passive films) on their surfaces and these prevent, or slow down, their corrosion process.Anodized titanium earringsThe thickness of the titanium oxide on the metal surface refracts the light and causes the rainbow colors on her earrings.Stainless steel eyeglassesThis passive film of only about a

7、 dozen atoms thick can be protective.1 兵器：长期贮存，使用环境恶劣2 交通运输：对铁轨、机车的腐蚀， 对飞机零部件的腐蚀；（超高强度铝合金-应力腐蚀） 船舶的海水腐蚀；3 能源电力： 火电有锅炉和管道的腐蚀， 水电有水轮机组的腐蚀； 核电站蒸汽发生器的腐蚀；（高镍合金-晶间腐蚀） 煤矿安全；（井下湿度大、磨损腐蚀） 石油，油气开采和运输造成设备和管道的腐蚀。4 机械电子产品:机床、电器5 化工设备：管道、锅炉、储存、阀门、冷凝；6 建筑物:钢筋混凝土的盐害7 民生：自来水管的锈蚀；8 环境污染Uncontrolled corrosion may lead

8、 to disastrous consequencesLoss caused by corrosiono 在化学工业、石油化工、造纸等工业中，金属腐蚀造成设备的跑、冒、滴、漏可造成大量有毒的物质泄漏，污染环境，危害人民的健康。因此，研究与解决材料的腐蚀问题，与防止环境污染、保护人民的健康息息相关.o 每年由于腐蚀可使大约1020的金属损失掉了。2003 年世界的钢产量达到9.625 亿吨，中国的钢产量高达2.2亿吨，美国的钢产量为0.914亿吨。按下限计算，世界每年腐蚀掉的钢大于美国的钢产量；中国一年就有2200万吨钢被腐蚀掉了，相当于腐蚀掉一个大型钢铁企相当于腐蚀掉一个大型钢铁企业的年产量。

9、业的年产量。腐蚀事故举例o 1966年某天然气井的套管发生硫化物应力腐蚀开裂，造成井喷和特大爆炸，人员伤亡，日产百万立方米的高产气井报废。o 1971年某天然气管线发生腐蚀断裂，产生爆炸， 直接经济损失达7000 万元。o 1997年某化工厂年18个乙烯原料储罐由于硫化物腐储罐引起大火，停产半年，直接损失达2亿多元，间接损失巨大。o 1985年日本的一架波音747客机，由于应力腐蚀断裂，死亡500余人。塔里木油田某井油管CO2腐蚀形貌图含硫输气管线沿着焊缝开裂失效Classification of corrosionCharacter of corrosion breakage:Uniform

10、 Corrosion (general Corrosion)l The surface effect produced by most direct chemical attacks (e.g., as by an acid) is a uniform etching of the metal.Galvanic Corrosion 电偶腐蚀电偶腐蚀l Galvanic corrosion is an electrochemical action of two dissimilar metals in the presence of an electrolyte and an electron

11、conductive path. It occurs when dissimilar metals are in contact.Pitting corrosion（点蚀）l Pitting corrosion is localized corrosion that occurs at microscopic defects on a metal surface.l The pits are often found underneath surface deposits caused by corrosion product accumulation.Crevice Corrosion 缝隙腐

12、蚀缝隙腐蚀l Crevice or contact corrosion is the corrosion produced at the region of contact of metals with metals or metals with nonmetals. l It may occur at washers, at sand grains, under applied protective films（薄膜）, and at pockets formed by threaded joints.Filiform Corrosion 丝状腐蚀丝状腐蚀l This type of cor

13、rosion occurs on painted or plated surfaces when moisture permeates the coating.l Long branching filaments（细丝） of corrosion product extend out from the original corrosion pit and cause degradation of the protective coating.Intergranular Corrosion 晶间腐蚀l Intergranular corrosion is an attack on or adja

14、cent to the grain boundaries（晶界） of a metal or alloy.Stress Corrosion Cracking应力腐蚀断裂应力腐蚀断裂o Stress corrosion cracking (SCC) is caused by the simultaneous effects of tensile stress（拉应力） and a specific corrosive environment.o Stresses may be due to applied loads, residual stresses from the manufacturi

15、ng process, or a combination of both.Corrosion Fatigue 腐蚀疲劳腐蚀疲劳o Corrosion fatigue is a special case of stress corrosion caused by the combined effects of cyclic stress（循环应力） and corrosion. No metal is immune from some reduction of its resistance to cyclic stressing if the metal is in a corrosive en

16、vironment.Fretting Corrosion 微动腐蚀微动腐蚀o The rapid corrosion that occurs at the interface between contacting, highly loaded metal surfaces when subjected to slight vibratory motions is known as fretting corrosion.Erosion Corrosion 磨损腐蚀磨损腐蚀 o Erosion corrosion is the result of a combination of an aggre

17、ssive（侵蚀性） chemical environment and high fluid surface velocities.Dealloying 脱合金成分腐蚀脱合金成分腐蚀l Dealloying is a rare form of corrosion found in copper alloys, gray cast iron, and some other alloys.l Dealloying occurs when the alloy loses the active component of the metal and retains the more corrosion

18、resistant component in a porous “sponge”（海绵） on the metal surface.Hydrogen Damage 氢损伤氢损伤o Hydrogen embrittlement is a problem with high strength steels, titanium, and some other metals.o Control is by eliminating hydrogen from the environment or by the use of resistant alloys.Microbial Corrosion 微生物

19、腐蚀微生物腐蚀o Microbial corrosion (also called microbiologically - influenced corrosion or MIC) is corrosion that is caused by the presence and activities of microbes（微生物）.o This corrosion can take many forms and can be controlled by biocides（杀菌剂） or by conventional corrosion control methods.Concentratio

20、n CellCorrosion 浓差电池腐蚀浓差电池腐蚀o Concentration cell corrosion occurs when two or more areas of a metal surface are in contact with different concentrations of the same solution.Corrosion in Concrete 混凝土腐蚀混凝土腐蚀o Concrete is a widely-used structural material that is frequently reinforced with carbon stee

21、l reinforcing rods（钢筋）, post-tensioning cable or prestressing wires. The steel is necessary to maintain the strength of the structure, but it is subject to corrosion.Classification of corrosiono According to corrosion environments (腐蚀环境 )A corrosion in nature environments (自然环境中的腐蚀)大气腐蚀、淡水和海水腐蚀、土壤腐蚀

22、、细菌腐蚀B corrosion in industrial environments(工业环境介质中的腐蚀)在酸性溶液中、碱性溶液中、盐类溶液、工业水、熔盐中的腐蚀。腐蚀分类o According to corrosion mechanism(腐蚀反应机理) Chemical corrosion化学腐蚀、electrochemical corrosion电化学腐蚀、physical corrosion物理腐蚀。化学腐蚀：化学腐蚀：材料表面与非电解质直接发生纯化学作用而引起的破坏。oxidation电化学腐蚀：电化学腐蚀：材料表面与离子导电的介质因发生电化学作用而产生的破坏。 物理腐蚀：物理腐

23、蚀：材料由于单纯的物理溶解作用所引起的破坏。 Comparation of chemical corrosion and electrochemical corrosiono Chemical corrosion：金属表面与环境组分直接发生纯化学反应而引起的破坏 （no current）o Electrochemical corrosion：金属表面与环境组分(电解质溶液)发生电化学作用而产生的破坏。（Two electrodes，current ）ZnH2SO4ZnPtContents of corrosion course腐蚀课程的内容 o研究并确定金属材料与环境介质作用的普遍规律普遍规律，既从热力学研究金属腐蚀进行的可能性，更重要的是从动力学研究腐蚀进行的速率及机理。o研究在各种条件下控制或防止控制或防止腐蚀的措施，以把腐蚀控制在合理的程度上。o研究金属腐蚀速率的测试方法和技术，找出评定金属腐蚀的试验方法和标准；同时研究现场金属腐蚀的测试技术及监控方法。 What is corrosion? What are the main classes of corrosion? List five corrosion forms and give their character.