本文選題：液相等離子電解 + 溫度計算模型　； 參考：《南京理工大學(xué)》2017年碩士論文

【摘要】：本文研究了陰極液相等離子電解過程中,Ti-6Al-4V鈦合金工件表面溫度的計算與測量。研究從直流和脈沖兩個方面建立計算模型并驗(yàn)證。直流條件下采用已有的工件-氣膜-電解液模型進(jìn)行計算,并在原有模型基礎(chǔ)上修改了假設(shè)條件,考慮了電解液揮發(fā)消耗熱量對于工件表面溫度的影響。采用Excel對模型進(jìn)行計算,并對計算模型進(jìn)行驗(yàn)證,實(shí)驗(yàn)測量結(jié)果證明,修正后的直流模型計算數(shù)值與測量值能夠更好的擬合。直流條件下陰極工件表面溫度隨著電壓升高而增大;在電壓不變的情況下,陰極表面溫度隨著放電時間的延長而降低。脈沖條件下的溫度模型以一個脈沖周期為單位,討論斷電階段工件表面熱傳導(dǎo)的不同情況,建立了三種物理模型,分別考慮斷電階段工件與電解液之間存在蒸汽膜并發(fā)生熱交換、工件與電解液直接發(fā)生熱交換、工件不與外界發(fā)生熱交換三種情況,并根據(jù)邊界條件進(jìn)行求解得到了脈沖條件下陰極工件工件表面的溫度計算模型。將計算值與實(shí)驗(yàn)測量值相擬合,發(fā)現(xiàn)在斷電階段不考慮工件與外界的熱交換的情況下,計算模型最符合測量結(jié)果。在脈沖電壓下,工件表面溫度隨著占空比的增大而上升;而脈沖電壓的頻率減小,陰極起弧所需的電壓增大,但是頻率對于陰極工件表面溫度的影響不大。對直流和脈沖條件下不同溫度對工件表面滲層形貌與性能進(jìn)行分析。在直流條件下,隨著表面溫度的升高,滲層的厚度增加,硬度同時也得到提高,Ti-6Al-4V表面溫度到達(dá)847℃時,處理20min能夠在表面得到約100μm厚的滲層,滲層中主要為鈦的氧化物和碳氮化物,滲層中最大硬度可以達(dá)到1287.8HV0.1。脈沖條件下Ti-6Al-4V表面溫度升高同樣能使?jié)B層厚度增加,在867℃C時得到的滲層約為110μm,但是滲層中出現(xiàn)斷裂和剝落的現(xiàn)象較為嚴(yán)重。
[Abstract]:The calculation and measurement of workpiece surface temperature of Ti-6Al-4V titanium alloy during cathodic liquid plasma electrolysis have been studied in this paper. The calculation model of DC and pulse is established and verified. The existing workpiece-film-electrolyte model is used for calculation under DC condition. The hypothesis is modified on the basis of the original model, and the influence of the volatile heat consumption of electrolyte on the surface temperature of the workpiece is considered. Excel is used to calculate the model and verify the calculation model. The experimental results show that the modified DC model can better fit the calculated value and the measured value. The surface temperature of cathode workpiece increases with the increase of voltage under DC condition, and decreases with the prolongation of discharge time under the condition of constant voltage. The temperature model under pulse condition is used as a unit of pulse period to discuss the different conditions of heat conduction on the surface of workpiece during the period of power failure, and three kinds of physical models are established. Considering the existence of steam film and heat exchange between workpiece and electrolyte during power off stage, the heat exchange occurs between workpiece and electrolyte directly, and there is no heat exchange between workpiece and outside. According to the boundary condition, the temperature calculation model of cathode workpiece surface under pulse condition is obtained. By fitting the calculated values with the experimental measurements, it is found that the calculation model is the most suitable for the measurement results when the heat exchange between the workpiece and the outside world is not considered in the power off stage. Under the pulse voltage, the surface temperature of the workpiece increases with the increase of duty cycle, while the frequency of the pulse voltage decreases and the voltage required for the cathode arcing increases, but the frequency has little effect on the surface temperature of the cathode workpiece. The morphology and properties of the coating on the surface of the workpiece were analyzed at different temperatures under DC and pulse conditions. Under DC condition, with the increase of surface temperature, the thickness of permeation layer increases, and the hardness is also increased. When the surface temperature of Ti-6Al-4V reaches 847 鈩，

本文編號：1844873