發(fā)布時間：2018-09-14 11:00

【摘要】：接地網(wǎng)是變電站中用于防雷電、靜電和故障電流等十分重要的裝置。在我國,接地網(wǎng)主要為鋼鐵材料,其在土壤中會受電化學(xué)腐蝕,逐漸變薄,甚至銹蝕斷裂。接地網(wǎng)材料在土壤中的腐蝕是最重要的實際腐蝕問題之一。然而,目前對于接地網(wǎng)材料在土壤中的腐蝕行為研究,主要采用室外現(xiàn)場埋片法、模擬土壤溶液法和土壤飽和溶液法等,這些方法具有試驗周期長、耗費人力物力等特點,腐蝕過程甚至腐蝕機理都可能與真實土壤腐蝕不同。因此,建立一套能適用于不同理化性質(zhì)的土壤,并快速檢測、評價接地網(wǎng)材料耐土壤腐蝕性的方法尤為重要。 本文以華南某地酸性土壤為參考土壤體系,采用硅藻土模擬土壤實驗室加速腐蝕法,借助物理化學(xué)相分析、掃描電鏡、電化學(xué)工作站及激光拉曼光譜等手段系統(tǒng)研究了孔隙率、含水率、鹽含量、pH值等土壤理化性質(zhì)對接地網(wǎng)材料Q235鋼的腐蝕規(guī)律；對比了Q235鋼與X65鋼在模擬土壤與真實土壤腐蝕環(huán)境介質(zhì)下的腐蝕行為；還探討了影響Q235鋼和低合金1Cr鋼在模擬土壤的腐蝕規(guī)律及腐蝕速率差異的原因。通過研究得出以下結(jié)論： 模擬土壤的孔隙率、含水率、鹽含量、pH值等理化性質(zhì)對Q235鋼的腐蝕影響大小不一。隨模擬土壤中細硅藻土比例增加,Q235鋼腐蝕速率逐漸增大；含水率對Q235鋼的腐蝕影響存在一個極大值,30%時腐蝕速率最大；就本論文中研究的鹽含量因素的變化對腐蝕速率影響區(qū)別不大；Q235鋼的腐蝕速率隨模擬土壤的pH值升高而降低。 Q235鋼和X65鋼分別在模擬土壤和真實土壤兩種腐蝕環(huán)境介質(zhì)下腐蝕試驗一個月的結(jié)果表明,每種材料在兩種土壤環(huán)境下呈現(xiàn)相似的腐蝕行為。兩者都由不均勻的點蝕發(fā)展為較為均勻的全面腐蝕,并且腐蝕速率具有一定的規(guī)律性,電化學(xué)極化行為表現(xiàn)為陽極活化控制,自腐蝕電位出現(xiàn)正移,腐蝕產(chǎn)物也主要由a-FeOOH、Fe3O4、Fe2O3組成。同時,與真實土壤腐蝕情況相比,在模擬土壤條件下兩種材料的腐蝕具有加速性,約是其2-3倍,生成的銹層也更厚、更致密、不易脫落。各試樣間的腐蝕狀況具有良好的重現(xiàn)性。 在模擬土壤腐蝕環(huán)境介質(zhì)中可以區(qū)分Q235鋼和低合金1Cr鋼這兩種材料的耐酸性土壤腐蝕的能力,Q235鋼的耐蝕性相對較差,其年腐蝕速率可達0.68mm/a,約是1Cr鋼的2倍；隨腐蝕周期的延長,腐蝕銹層還出現(xiàn)分層的現(xiàn)象,1Cr鋼的銹層致密、不易脫落,Q235鋼的銹層疏松、保護性差。
[Abstract]:Grounding grid is a very important device for lightning protection, static electricity and fault current in substation. In China, the grounding grid is mainly made of iron and steel, which will be corroded by electrochemistry, gradually thinned or even corroded and broken in soil. The corrosion of grounding grid materials in soil is one of the most important practical corrosion problems. However, at present, the corrosion behavior of grounding grid materials in soil is studied mainly by outdoor field burying method, simulated soil solution method and soil saturated solution method. These methods have the characteristics of long test period, consuming manpower and material resources, etc. The corrosion process and even the corrosion mechanism may be different from the real soil corrosion. Therefore, it is very important to establish a set of methods that can be applied to soil with different physical and chemical properties, and quickly detect and evaluate the soil corrosion resistance of grounding grid materials. In this paper, the porosity of acidic soils in South China was studied by means of physical and chemical phase analysis, scanning electron microscope, electrochemical workstation and laser Raman spectroscopy, using diatomite simulated soil laboratory accelerated corrosion method. Physical and chemical properties of soil such as water content, salt content and pH value, corrosion behavior of Q235 steel was compared with that of X65 steel in simulated soil and real soil corrosion environment. The influence of Q235 steel and low alloy 1Cr steel on the corrosion law of simulated soil and the difference of corrosion rate were also discussed. The main conclusions are as follows: the physical and chemical properties of simulated soil such as porosity, water content, salt content and pH value have different effects on the corrosion of Q235 steel. The corrosion rate of Q235 steel increases gradually with the increase of the proportion of fine diatomite in simulated soil, and the effect of water content on the corrosion of Q235 steel has a maximum value, and the corrosion rate is the highest at 30%. The change of salt content in this paper has little effect on corrosion rate. The corrosion rate of Q235 steel decreases with the increase of pH value of simulated soil. The results of corrosion test of Q235 steel and X65 steel in simulated soil and real soil for one month show that the corrosion rate of Q235 steel decreases with the increase of pH value of simulated soil. Each material exhibits similar corrosion behavior in both soil environments. Both of them have developed from non-uniform pitting to more uniform corrosion, and the corrosion rate has certain regularity. The electrochemical polarization behavior is controlled by anodic activation, the self-corrosion potential is positively shifted, and the corrosion products are mainly composed of a-FeOHF3O4Fe3O4Fe2O3. At the same time, compared with the real soil corrosion, the corrosion of the two materials is accelerated under simulated soil conditions, which is about 2-3 times, and the rust layer is thicker, denser and less easy to fall off. The corrosion condition among the samples has good reproducibility. The corrosion resistance of Q235 steel and low alloy 1Cr steel can be distinguished in simulated soil corrosion environment medium. The corrosion resistance of Q235 steel is relatively poor. The annual corrosion rate of Q235 steel can reach 0.68 mm / a, which is about twice as high as that of 1Cr steel. The corrosion rust layer is also delaminated. The rust layer of 1Cr steel is dense, and the rust layer of Q235 steel is not easy to fall off. The rust layer of Q235 steel is loose and the protection is poor.
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM63;TM862

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