After a short hiccup, everyone's conversation returned to the machines in production in front of them.

Ma Liping took Chang Haonan up the steps and came to a row of operating cabinets:

"In fact, after the performance parameters of the turbine blades of the turbofan 10 were determined, we also tried to produce a batch of products with new equipment, and the other parts were okay, although there were some flaws, but they could be recovered through subsequent finishing."

"Only the final solidification process is very difficult to control, and the single crystal produced has great defects at the crystal level, and even a large part of it is not a single crystal, which cannot be remedied in the future anyway, so we have to temporarily stop work and wait for the process problem to be solved before re-production."

As he spoke, he took out a packaged turbine blade from the side and handed it to Chang Haonan:

"This is one of the most typical of our previous batch of scrap."

"Heterocrystals, freckles, component segregation, high oxygen and nitrogen content, large primary dendrite spacing, crystal orientation deviation from the direction of force, in short, the single crystal defects written in the textbook, this product is all collected."

"Even if you want to deliberately produce such a waste product, it is difficult to do it, if this thing is not related to the Taihang project and needs to be kept secret, I want to take it out to show my students......

Chang Haonan took the leaf and looked at it over and over again.

Of course, it is impossible to see anything with the naked eye, and the difference in crystal morphology may not be able to be seen completely even with a general optical microscope, and special equipment is required to detect it.

"Now the turbofan 10 is still in the research and development stage, and everything involved in the project is naturally top secret, but after the finalization, these waste products are not so sensitive, although it is not possible to take them away directly, but you can take out the crystal form photos."

He said to return the "perfect" scrap to Ma Liping:

"So, you think it's a matter of adjusting the parameters of the solidification process?"

"Naturally, yes."

The latter nodded:

"The solidification technology used in this set of equipment is the most popular high-speed solidification method, which realizes the control of the temperature gradient through the thermal insulation heating zone in the furnace and the water-cooled tray at the bottom of the casting and radiant heat dissipation."

"However, in the process of pulling the casting out of the insulation area, the heat dissipation gradually becomes mainly radiation, and the heat dissipation efficiency drops sharply, resulting in a continuous decrease in the temperature gradient at the solidification front, and the produced castings are prone to defects, and the larger the single crystal size, the more obvious the defects."

"When foreign countries use the high-speed solidification method to produce blades, it is also necessary to fine-tune the pulling speed, because the heat dissipation efficiency of the thermal radiation process cannot be controlled, so the temperature gradient of the water-cooled part can only be reduced as much as possible, so that the whole gradual temperature distribution is more even."

Ma Liping's expression was a little complicated, so much so that Chang Haonan stood in place and thought for a while after hearing it:

"If that's the case, even if we finally find a process that can stably form a single crystal, the production efficiency should be very low?"

"Uh......"

Ma Liping wiped the sweat on his forehead:

"Mr. Chang, the reason why this method is called the high-speed solidification method is that it is very fast compared with the traditional power reduction method."

"It's just that the size of the blade of the turbofan 10 is indeed a bit too large, and the shape is relatively complex, so it can only be worked slowly, which is also the main reason for the overall low production efficiency of the third-generation aero engine......

Obviously, he thought that Chang Haonan was not satisfied with their production efficiency.

The latter, however, waved his hand:

"No, I mean, since the cold end is much less efficient at cooling by heat radiation than with a water disc, why not just cool the entire workpiece with liquid?"

"Huh?"

Ma Liping was directly stunned, and only after a while did he speak with difficulty:

"It's all liquid, isn't that quenching?"

"And water cooling is too good for the growing crystals, and the crystals that are suddenly exposed to low temperatures will directly and uncontrollably swell, and the crystal form cannot be guaranteed at all, and it is ......"

Before he finished speaking, he was interrupted by Chang Haonan, who was almost unable to hold back:

"Of course, it can't be water, the difference between the freezing point and the boiling point of water is only 100°C, and the range is too narrow for cold end temperature control to be operated at all."

"What I mean is that the liquid with high thermal conductivity, high boiling point, low freezing point and large heat capacity is used to soak the roots of the drawn blades directly in it, and use heat conduction for intensive cooling, so that the temperature gradient of the entire workpiece can be large and stable, and the crystallization speed and crystal quality can also be guaranteed at the same time."

"High boiling point, low freezing point, and large heat capacity......"

Ma Liping looked at the sky with his eyes and thought for a moment.

He wanted to say how could there be such an amazing thing.

But he soon realized that he had thought wrong.

There is a large group of materials that meet this requirement, but they are not usually considered "liquids".

"That's all there ...... Liquid metal? ”

Chang Haonan nodded:

"If I think about it at first, it is best to use aluminum or tin, as you said, the freezing point should not be too low, otherwise the sudden strong cold will also have an adverse effect on crystal growth."

This time, Ma Liping did not respond immediately, but paced back and forth in front of the cabinet, obviously thinking about the feasibility of this technical route.

"Mr. Chang, if you use liquid metal, there are more operational variables that need to be controlled, especially if the cooling rate is increased."

After a few minutes, he stopped again and looked at Chang Haonan:

"At the very least, we need to consider the temperature change of the liquid metal itself after it comes into contact with the crystal, and even if the thermal conductivity is relatively large, because of the lack of fluidity, a new temperature field will be formed inside the liquid, and this temperature field must be controlled at the same time, and it must also be considered that our heating method itself is also uneven......

Don't talk about calculating, even just thinking about it, it makes Ma Liping feel big.

"What if you use a uniform heating method, such as microwave heating?"

Zhong Shihong, who had been unable to speak next to him, suddenly proposed:

"This reduces the ...... of at least one variable"

Before he finished speaking, he saw two people on the other side looking at him with complicated eyes.

"You...... To use a microwave...... Heating metal? ”

Ma Liping's voice was a little incredulous.

Just like when he first faced Chang Haonan.

It's just that he doubted whether his level was not enough before, and now he doubted Zhong Shihong's intelligence......

Microwaves have a skin-like effect on metals, and can only penetrate a very shallow surface layer of metal, and cannot be heated from the inside as a whole, like boiling water.

"It's all right......"

Zhong Shihong, who realized that he had a bad idea, immediately shut up.

"In short, if liquid metal is introduced, the control logic will be extremely complex, including our next step of process optimization, and the difficulty of optimization will increase exponentially with each additional parameter introduced......"

"We ...... Can you really get results in a few months? ”

When the complexity of the model is large enough, it is difficult to calculate the results even with a computer.

Especially at present, Huaxia's supercomputer is still much worse than the international leading level in terms of hard indicators.

"What ...... this?"

Chang Haonan pushed the helmet on his head:

"It's hard for me to say about others, but since I'm in charge, it shouldn't be a big problem......"

(End of chapter)