Chapter 437: Vacuum

Chapter 437
[Let r be the minimum average radius of the ultrafine powder, o be the surface tension of the molten metal, ￡o be the dielectric constant under vacuum, be the coefficient related to the field strength, G be the amount of droplets formed per unit time, U be the DC high voltage , I is the field emission current. The formula relationship between the average radius of the ultrafine powder and the relevant parameters such as DC high voltage is: r=6ε0Gσ/√ε0IU+2σ(3ε0GI/U).]
[Suppose the resistance along the way when the melt flows in the capillary tube is P, λ is the resistance coefficient along the way, d is the pipe diameter, is the average flow rate, and P is the density of the melt. When viscous liquid flows in a capillary, laminar flow occurs. Assuming that the flow of alloy melt in the capillary is a stable laminar flow, according to the Dary formula, the resistance P1 along the way when the alloy melt flows in the capillary is: P1=λl/dpv^2/2, then...]
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Cheng Nuo listed the relationship between experimental independent variables and the particle size of the ultra-nano powder obtained on the paper.
With the formulas listed, Cheng Nuo's thinking became clearer.
"Under the condition that the size of the DC high voltage remains unchanged, the size of the nano ultrafine powder should be non-linear attenuation as the emission frequency of the droplet increases, but when the emission frequency of the droplet increases to 57 Hz, the size becomes linear. The relationship is slowly increasing."
"However, the pressure for conveying the melt is different. When the pressure of the alloy melt flowing in the capillary increases, the additional pressure generated on the surface when the melt forms a liquid cone at the front end of the quartz glass capillary will also increase. The relationship between the two is in line with C curvature formula. So, then..."
As he spoke to himself, Cheng Nuo's eyes became brighter.
Looking down at the experimental data record sheet at hand, Cheng Nuo's mouth twitched slightly.
"I think, I already know where the problem is." Cheng Nuo said silently in his heart.
On the other side, the older professor saw that Cheng Nuo hadn't moved for a long time, so he stopped focusing on Cheng Nuo's side.
Even if Cheng Nuo was really capable of helping them solve their current difficulties, he didn't think Cheng Nuo could do it within an hour.
Now that he has time to calm down, the older professor gradually feels that what he said just now is indeed a bit extreme.
In other words, Cheng Nuo is also a talented and intelligent young man. It is common to be competitive. As seniors, the two of them really shouldn't push each other so aggressively.
Fortunately, I didn't say just now what should be done if Cheng Nuo fails, otherwise it would not be right to let him do it, and it would not be right to not do it, and it would be in a dilemma.
This is just right. After the time passed, I went up to sympathize with him, and then tactfully told him that it would be difficult for him to take up this task, so that the director would be replaced by another person, so as not to hurt Cheng Nuo's face.
This is already planned in my mind, and a picture has appeared in my mind.
Just as the older professor was about to pour himself a cup of tea to moisturize his throat, he saw that the teapot on the table was empty, and was about to get up to make another pot.
Halfway through getting up, I turned my head and saw the figure suddenly appeared on his side. I was scared to sit on the chair, and the teapot fell on the ground with a clatter.
"Cheng Nuo, when did you come here? Why is there no sound at all?"
"I have been here for a while, professor, I saw you just now in a daze. I don't know what I'm thinking, so I can't bear to disturb you."
The older professor coughed slightly and blushed slightly.
Of course he can't tell Cheng Nuo, what he fantasizes about later is how to "teach" Cheng Nuo in an elderly attitude.
Avoiding this topic, the older professor picked up the teapot on the ground and asked, "Isn't Mr. Cheng Nuo checking the experimental data over there? Come to me so quickly, have you found the problem?"
The older professor's tone was full of smiles.
Less than forty minutes passed, he didn't think Cheng Nuo had discovered a problem in the experiment.
You know, although he and the younger professor are both physicists, they do not separate in mathematics and science. The two can reach such high attainments in physics, and their mathematics is not too bad. At least compared to doctoral students majoring in mathematics at top universities.
But even so, the two of them pondered this question for three or four days and didn't figure out any clues.
As for Cheng Nuo, it took 40 minutes to figure it out...
He didn't think he was really that unbearable.
The older professor guessed that Cheng Nuo was 80% seeing the end of time and hopeless to win, so he came here to take the matter lightly.
If this is the case, then I don't mind selling Cheng Nuo's face, as this has never happened.
Anyway, listening to Mr. Klein's opinion, Cheng Nuo will probably stay in the institute for a while. In the future, there is no need to deliberately engage in hostility if you will not see when you look up.
However, all this is just the older professor's own guess.
Under the sluggish gaze of the older professor, Cheng Nuo slowly nodded, pushed the draft paper in front of the older professor, grinned, "Yes, I have found the reason for your experiment failure."
Seeing that the older professor did not respond, Cheng Nuo continued to explain, "I have derived formulas for all independent variables that affect the particle size of nano ultrafine powders, and finally obtained eight calculation relations, as well as their respective scope of application."
"Then I compared the experimental record data you gave me and found the problem."
Cheng Nuo used his finger to press the words circled on the draft paper.
"Vacuum?" The older professor finally reacted.
Cheng Nuo nodded, "Yes, it is the degree of vacuum. After calculation, I found that although the direct influence of the vacuum degree in the vacuum chamber on the process of melting and dropping the alloy into nano ultrafine powder is almost negligible, the degree of vacuum can indirectly affect the vacuum chamber. The nozzle pressure of the capillary, the dielectric constant, etc. are seven or eight variables."
The degree of vacuum is simply the degree of thinness of gas in a vacuum state.
"We really didn't notice this." The older professor pondered for a moment and carefully pondered what Cheng Nuo had said. "In other words, the reason why we failed before was because we ignored the influencing factor of vacuum."
"It can be said ~EbookFREE.me~ Now that you have found the problem, you must have found a suitable solution?"
"After my calculations, as long as the vacuum in the vacuum chamber is adjusted to the range of 1.3mPa~1.5mPa, the nano ultrafine powder that meets the specifications can be produced."
"Really?" The older professor had already believed Cheng Nuo's words.
"Yes or not, don't you know after an experiment?" Cheng Nuo smiled lightly.
The older professor nodded in agreement.
Ask the young professor to borrow a vacuum pump from the next laboratory, adjust the vacuum in the vacuum chamber to 1.3 mPa, and enter the remaining values ​​as normal.
With the dazzling light of the electric spark, the alloy melt is broken down into fine particles.
Observed under the electron microscope, after some busy work, the average particle size was finally 84, which fully met the standards of nano ultrafine powder.