【摘要】：由于鋅具有低的腐蝕電位和腐蝕速率,其成為鋼鐵腐蝕防護的理想材料。但在不同地區(qū),鋅涂層的防腐效果千差萬別,壽命長短不一。為尋找這些差別原因,以往通過對經長期暴露試樣腐蝕消耗量的測量、腐蝕產物的解剖觀察等方法,了解科學研究所需的信息。但是,受大氣環(huán)境復雜性和腐蝕失效周期過長的限制,這種方法的有效性和時效性屢屢受到詬病。至今,還未能充分掌握鋅涂層在自然大氣中的腐蝕失效規(guī)律。現(xiàn)有的實驗室模擬環(huán)境加速腐蝕試驗及其它間接的評價手段,所獲數(shù)據(jù)量少、不能充分反映鋅的大氣腐蝕隨時間的變化過程,給研究鋅的大氣腐蝕帶來極大困難,且易產生大的誤差。開展長期、連續(xù)、實時、原位的評價成為研究金屬在大氣環(huán)境中腐蝕的大勢所趨。因此,本文針對鋅的大氣環(huán)境腐蝕開發(fā)了新型大氣腐蝕檢測儀(ACM)。該ACM選用了惰性碳膜做陰極材料,有效地消除了傳統(tǒng)ACM中陰極材料的同步腐蝕引起的電化學性能改變,三層疊加結構使得電偶的陰極和陽極材料分別處在兩個平行平面上,避免了陽極腐蝕產物對陰極材料表面的影響,提高了傳感器的一致性和使用壽命。配套開發(fā)的ACM檢測儀采用了固態(tài)電池和太陽能電池板的雙供電模式,并利用GPRS實現(xiàn)了數(shù)據(jù)的遠程傳輸,減少了傳統(tǒng)暴露試樣法人工操作帶來的信息丟失和數(shù)據(jù)誤差,保證了鋅在真實大氣環(huán)境中腐蝕數(shù)據(jù)的穩(wěn)定。經野外環(huán)境、模擬環(huán)境及鋅表面改性等試驗表明,該ACM能夠滿足長時、連續(xù)、實時和原位的腐蝕檢測工作,是研究鋅在大氣環(huán)境中的腐蝕,掌握鋅的大氣腐蝕規(guī)律的有效手段。多因子循環(huán)復合實驗是模擬大氣環(huán)境腐蝕且具有加速性和重現(xiàn)性的重要手段,是研究金屬大氣腐蝕規(guī)律的有效工具,目前還沒有形成統(tǒng)一的規(guī)范和成熟的產品。為此,本文開發(fā)了5因素的復合模擬環(huán)境腐蝕試驗裝置,可精確調整、控制主要腐蝕影響因子和環(huán)境參數(shù)。試驗結果表明,該系統(tǒng)具有較好的加速效果。本文采用野外大氣環(huán)境和實驗室模擬環(huán)境相結合的方法,開展了Zn/C電偶型ACM的長期、實時和原位的檢測和熱浸鍍鋅試樣的腐蝕試驗,研究了大氣環(huán)境溫度、濕度對鋅腐蝕影響的規(guī)律；研究了環(huán)境中Cl-加速鋅腐蝕作用機制和對鋅腐蝕動力學影響的規(guī)律和特征；研究了環(huán)境中S02中間產物在鋅腐蝕中的競爭作用和鋅腐蝕動力學規(guī)律和特征。結論如下：鋅在大氣環(huán)境中的腐蝕速率受溫度與濕度的聯(lián)合作用影響。隨溫度和濕度的升高,鋅的腐蝕速率都會增大,其中濕度對腐蝕速率的影響作用較溫度明顯。并且溫度和濕度兩者之中的任何一個的升高都會加大另一個對鋅腐蝕速率的影響程度,即溫度和濕度對鋅腐蝕的影響存在耦合聯(lián)動作用機制。依據(jù)鋅在模擬環(huán)境中的腐蝕試驗數(shù)據(jù)建立的溫度、濕度對鋅溶解耦合影響的二元二次數(shù)學模型,得到了野外環(huán)境檢測數(shù)據(jù)的驗證。與潤濕時間(TOW)模型相比,耦合影響模型可更精確地反映大氣環(huán)境中溫度、濕度對鋅腐蝕行為的影響規(guī)律。鋅在不含侵蝕性離子大氣環(huán)境中的腐蝕,經歷了腐蝕初期階段電極反應控制的活化溶解到混合控制直至擴散控制的演變過程。經長期腐蝕后的鋅在無侵蝕性離子環(huán)境中的腐蝕動力學規(guī)律遵循冪函數(shù)模型。在含C1-的大氣環(huán)境中,由于表面有鹽的沉積,鋅的腐蝕能夠一直保持活化溶解狀態(tài)。隨腐蝕時間的延長,鋅腐蝕產物不能形成有效阻擋層,因而鋅在該環(huán)境中的腐蝕動力學呈線性規(guī)律特征。由于Cl-在鋅表面的吸附,使雙電層形成非線性電位區(qū),降低了鋅脫離基體的位能趨勢,使得鋅溶解活化能降低。隨Cl-濃度增加,鋅溶解速率增大。當Cl-吸附率達到極限值時,鋅溶解速率最大,繼續(xù)增大Cl-濃度,鋅的溶解會受到阻礙,溶解速率反而降低。在含SO2的大氣環(huán)境中,鋅的腐蝕除受酸化作用外,還受SO2中間產物SO32-和SO42-等離子競爭作用影響。SO32-在鋅表面形成難溶性亞硫酸鹽,其進一步氧化為硫酸鹽非常困難,對鋅的溶解形成阻礙作用。SO42-對鋅的溶解有加速作用,其加速機制與Cl-大致相同。當大氣中SO2濃度低于10ppm時,四價硫轉化為六價硫的比例較高,以SO42-的作用為主,鋅溶解速率較大。SO2濃度增大,四價硫轉化為六價硫比例降低,SO32-作用增強。當濃度達到10ppm時,SO32-在鋅表面的吸附達到極值,鋅溶解速率下降到谷值。SO2濃度繼續(xù)升高,超過10ppm時,SO42-濃度增大,溶液酸性增強,亞硫酸鹽溶解度增大,其阻擋作用削弱,使得鋅溶解速率再次呈上升趨勢。在一般含有SO2的大氣環(huán)境中,由于SO2濃度遠低于10ppm,四價硫氧化為六價硫趨勢較強,故其對鋅的腐蝕影響作用以SO42-的加速鋅溶解機制為主,從而能使鋅保持活化狀態(tài),使鋅在該種大氣環(huán)境中的腐蝕動力學遵循線性規(guī)律特征。
[Abstract]:Because of its low corrosion potential and corrosion rate, zinc has become an ideal material for corrosion protection of iron and steel. But in different regions, the anticorrosion effect of zinc coating varies widely and life span is different. However, the effectiveness and timeliness of this method are repeatedly criticized by the complexity of the atmospheric environment and the long period of corrosion failure. So far, the corrosion failure laws of the zinc coating in the natural atmosphere have not been fully understood. Price means, the amount of data obtained is little, it can not fully reflect the change process of atmospheric corrosion of zinc with time, which brings great difficulty to the study of atmospheric corrosion of zinc, and it is easy to produce large error. To carry out long-term, continuous, real time, in situ evaluation becomes the general trend of corrosion in the atmosphere. Therefore, this article is aimed at the atmospheric environment of zinc. Corrosion developed a new type of atmospheric corrosion tester (ACM). The ACM used inert carbon film as the cathode material, effectively eliminating the electrochemical performance changes caused by the synchronous corrosion of the cathode materials in the traditional ACM. The three layer superposition structure makes the cathode and anode materials in the two parallel planes, avoiding the anode corrosion products. The influence of the surface of the cathode material improves the consistency and service life of the sensor. The developed ACM detector adopts the dual power supply mode of the solid state battery and the solar panel, and uses the GPRS to realize the remote transmission of the data, which reduces the information loss and data error caused by the manual operation of the traditional exposed sample method, and ensures the zinc. The stability of corrosion data in real atmospheric environment. Through field environment, simulated environment and zinc surface modification, the results show that the ACM can meet the long-term, continuous, real-time and in-situ corrosion detection work. It is an effective means to study the corrosion of zinc in the atmosphere and master the atmospheric corrosion law of zinc. The multi factor cyclic compound experiment is a simulation. The important means of atmospheric corrosion and acceleration and reproducibility is an effective tool to study the corrosion law of metal atmosphere. At present, there is no unified standard and mature product yet. Therefore, this paper has developed a compound simulated environmental corrosion test device with 5 factors, which can be adjusted accurately and control the main corrosion factors and environmental parameters. The experimental results show that the system has good acceleration effect. In this paper, the long-term, real time, in situ and galvanized corrosion tests of Zn/C galvanic ACM are carried out by combining the field atmosphere environment with the laboratory simulation environment, and the influence of atmospheric temperature and humidity on zinc corrosion is studied. The mechanism of Cl- accelerated zinc corrosion and the regularity and characteristics of zinc corrosion kinetics in the environment. The competitive action of S02 intermediate products in the environment and the kinetics and characteristics of zinc corrosion were studied. The conclusions are as follows: the corrosion rate of zinc in the atmosphere is affected by the combination of temperature and humidity. The corrosion rate of zinc will increase, and the effect of humidity on the corrosion rate is more obvious. And the increase of any one of the temperature and humidity will increase the effect of another on the corrosion rate of zinc, that is, the coupling interaction mechanism between temperature and humidity affects the corrosion of zinc. The temperature of the corrosion test data in the environment and the two yuan two mathematical models of the influence of humidity on the coupling of zinc dissolve have been verified by the field test data. Compared with the wetting time (TOW) model, the coupling influence model can more accurately reflect the influence of temperature and humidity on the corrosion behavior of zinc in the atmosphere. The corrosion in the atmospheric environment has experienced the evolution process of the activation dissolution controlled by the electrode reaction in the initial stage of the corrosion to the mixed control and the diffusion control. The corrosion kinetics of zinc after long-term corrosion in the non erosive ion environment follows the power function model. In the atmospheric environment containing C1-, the surface has salt deposition, The corrosion of zinc can remain active and dissolved. With the prolongation of corrosion time, the zinc corrosion product can not form an effective barrier layer. Therefore, the corrosion kinetics of zinc in this environment is linear. The adsorption of Cl- on the zinc surface makes the double layer form a nonlinear potential area and reduces the potential trend of zinc detachment from the matrix, so that zinc is reduced. The dissolution activation energy is reduced. With the increase of Cl- concentration, the dissolution rate of zinc increases. When the Cl- adsorption rate reaches the limit value, the dissolution rate of zinc is the largest, and the Cl- concentration continues to increase. The dissolution of zinc will be hindered and the dissolution rate decreases. In the atmosphere containing SO2, the corrosion of zinc is also affected by the SO2 intermediate product SO32- and SO42- plasma. The competitive effect affects the formation of insoluble sulfite on the zinc surface, and its further oxidation to sulfate is very difficult. The dissolution of zinc has a hindering effect on the dissolution of zinc, and.SO42- accelerates the dissolution of zinc. The acceleration mechanism is roughly the same as that of Cl-. When the concentration of SO2 in the atmosphere is lower than 10ppm, the proportion of tetravalent sulfur to six is higher, SO42- The concentration of.SO2 is larger, the concentration of.SO2 is larger, the proportion of tetravalent sulfur is reduced to six, and the effect of SO32- is enhanced. When the concentration reaches 10ppm, the adsorption of SO32- on the zinc surface reaches the extreme value, the dissolution rate of zinc drops to the valley value and the.SO2 concentration continues to rise. When the concentration exceeds 10ppm, the concentration of SO42- increases, the solution acidity increases, and sulfite dissolves. As the degree of degree increases, the barrier effect is weakened, and the dissolution rate of zinc is on the rise again. In the atmospheric environment with SO2 generally, because the concentration of SO2 is far lower than that of 10ppm, the oxidation of tetravalent sulphur to six is stronger, so the effect of its corrosion to zinc is mainly based on the accelerated zinc dissolving machine of SO42-, thus making zinc active and zinc in its state. The corrosion kinetics in this atmosphere follows the linear rule.
【學位授予單位】：山東大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：TG172
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本文編號：2165100