universal data

Chapter 434 Vacuum Degree

437 chapter

[Suppose r is the minimum average radius of ultrafine powder, o is the surface tension of the molten metal, ￡ o is the dielectric constant under vacuum, μ is the coefficient related to the field strength, G is the amount of droplets formed per unit time, and U is the DC High voltage, I is the field emission current.Then the formula relationship between the average radius of the superfine powder and the relevant parameters such as DC high voltage is: r=6ε0Gσ/√ε0μIU+2σ(3ε0GI/μU).]

[Assume that the resistance along the way of the melt flowing in the capillary is P, λ is the resistance coefficient along the way, d is the pipe diameter, l is the length of the capillary that the melt flows through, v is the average flow velocity, and P is the density of the melt.When viscous liquids flow in capillaries, laminar flow often occurs.Assuming that the flow of the alloy melt in the capillary is a stable laminar flow, according to the Darcy formula, the resistance P1 along the way of the alloy melt flowing in the capillary is: P1=λl/dpv^2/2, then...]

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Cheng Nuo listed the relationship between the experimental variables and the particle size of the obtained ultra-nano fine powder in turn on the paper.

With the listing of the formulas one by one, Cheng Nuo's thinking became clearer.

"When the size of the DC high voltage remains unchanged, the size of the nano-superfine powder should decrease non-linearly as the droplet emission frequency increases. However, when the droplet emission frequency increases to 57 Hz, the size becomes linear. Relationships grow slowly.”

"But the pressure of transporting 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 consistent with C curvature formula. So, then..."

While talking to himself, Cheng Nuo's eyes became brighter.

Looking down at the experimental data record sheet at hand, Cheng Nuo's mouth curled up slightly.

"I think, I already know where the problem is." Cheng Nuo said silently in his heart.

On the other side, seeing that Cheng Nuo hadn't moved for a long time, the older professor stopped paying attention to Cheng Nuo.

Even if Cheng Nuo really had the strength to help the two of them solve their current predicament, he didn't think Cheng Nuo could do it within an hour.

Now that he had time to calm down, the older professor gradually felt that what he said just now was indeed a bit extreme.

How to put it, Cheng Nuo is also a talented young man, and it is common for him to be competitive.As seniors, the two of them really shouldn't be so aggressive.

Fortunately, I didn't say what to do if Cheng Nuo failed, otherwise, it would be wrong to let him do it, or not to do it, and he would be in a dilemma.

This is just right.After the time has passed, I will go up to offer my condolences kindly, and then tactfully tell him that it is difficult for him to take on such a big job, and ask the director to be replaced by someone else, so as not to hurt Cheng Nuo's face as much as possible.

I have already planned it in my mind, and the picture has emerged in my mind.

Just as the senior professor was about to pour himself a cup of tea to moisten his throat, he saw that the teapot on the table was empty, and was about to get up to make another pot.

In the middle of getting up, when he turned his head and saw a figure appearing suddenly beside him, he was so frightened that he sat down on the chair directly, and the teapot fell to the ground with a clang.

"Cheng Nuo, when did you come here? Why is there no sound at all?"

"I've been here for a while, professor. I just saw you were in a daze, thinking about something, so I didn't have the heart to disturb you."

The older professor coughed slightly and blushed slightly.

Of course, he couldn't tell Cheng Nuo that what he fantasized about was how to "teach" Cheng Nuo as an elder later.

Avoiding this topic, the senior professor picked up the teapot on the ground and asked, "Mr. Cheng Nuo is checking the experimental data over there. He came to me so quickly, so he has already found the problem?"

The older professor's tone was full of smiles.

Less than four or ten minutes had passed, and he didn't think Cheng Nuo had discovered the problems in the experiment.

You know, although he and the younger professor are both physicists, they have no distinction between mathematics and science. The physics level of the two can reach such a high level, and the mathematics level is not too bad.At least compared to the doctoral students majoring in mathematics in top universities, it is not in vain.

But even so, the two of them pondered over this question for three or four days, but they didn't come up with any clues.

As for Cheng Nuo, it took four to ten minutes to figure it out...

He didn't think he was really that bad.

The older professor guessed that Cheng Nuo most likely saw that time was running out and there was no hope of victory, so he came here to brush the matter off lightly.

If this is the case, then I don't mind selling Cheng Nuo's face as if it never happened.

Anyway, according to Mr. Clay, Cheng Nuo probably will stay in the research institute for a while.In the future, if you don't look up and see you when you look down, there is no need to deliberately turn against each other.

However, all this is just the old professor's own guess.

Under the older professor's dull gaze, Cheng Nuo nodded slowly, pushed the draft paper in front of the older professor, and grinned, "That's right, I've found out the reason why your experiment failed."

Seeing that the senior professor did not respond, Cheng Nuo continued to explain, "I have deduced all the independent variables that affect the particle size of the nano-ultrafine powder, and finally came up with eight calculation relations, and their respective scopes of application."

"Then I compared the experimental record data you gave me, and found the problem."

Cheng Nuo pressed his fingers on the words circled heavily on the draft paper.

"Vacuum?" The elderly professor finally responded.

Cheng Nuo nodded, "That's right, it's the degree of vacuum. After calculation, I found that although the direct effect of the degree of vacuum in the vacuum chamber on the process of alloy melting and dripping into nano-ultrafine powder can be almost negligible, the degree of vacuum can indirectly affect the degree of vacuum in the vacuum chamber. Capillary nozzle pressure, dielectric constant, ... seven or eight variables."

Vacuum, in simple terms, is the degree of thinness of gas in a vacuum state.

"We really didn't notice this." The older professor pondered for a moment, carefully pondering Cheng Nuo's words, "That is to say, the reason we failed before was because we ignored the influencing factor of vacuum degree."

"you can say it this way."

"Since you have discovered the problem, you must have found a suitable solution, right?"

"According to my calculations, as long as the vacuum degree 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 begun to believe Cheng Nuo's words.

"Yes or no, don't you know by experimenting?" Cheng Nuo smiled lightly.

The older professor nodded approvingly.

Ask the young professor to borrow a vacuum pump from the laboratory next door, adjust the vacuum degree in the vacuum chamber to 1.3mPa, and input the rest of the values ​​according to the normal values.

With the dazzling light of the electric spark, the molten alloy is broken down into fine particles.

Observation under the electron microscope, after a lot of busy work, the average particle size was finally found to be 84, which fully meets the standard of nano-ultrafine powder.

(End of this chapter)