Chapter 1405: Subverted, but not in the way you think

When Chang Haonan returned to Beijing from Longyuan Province and saw the bizarre infrared emission spectrum, he was a little surprised at first.

"Have you confirmed this result?"

He asked Li Yabo who was standing beside him with some doubt.

This report from the Institute of Aeronautical Materials was only five pages long, but he had been holding it in his hands for more than an hour.

The edges of the paper became frayed due to repeated rubbing.

Chang Haonan did not suspect that the subordinate units within the aviation industry system were falsifying data. Besides, even if they were falsified, they would not voluntarily send the data to him.

But this spectrum is really too coincidental.

The low emissivity feature is almost strictly limited to the two atmospheric observation window bands. Not to mention detection, even if he was given a blank coordinate paper to draw freely, he would not dare to draw such a data curve.

What is even more bizarre is that the report specifically noted that the material of this sample was scraped directly from a WS-10G verification aircraft that had completed its mission, and technicians were unable to reproduce the same results using newly synthesized material of the same model.

You can't say that WS-10G is some kind of holy land that can add buffs to materials, right?

"Confirmed."

Li Yabo took off his goggles and nodded:

"Researcher Peng from the Institute of Aeronautical Materials submitted the material report last week. I have been repeating the test before you came back. In general, although the reproducibility is not very good, there are still three times of repeated results that are basically completely consistent. It can be considered that this material has extremely strong spectral selectivity under certain specific conditions..."

Chang Haonan touched his chin, but did not have too many questions about the reproducibility issue.

The daily work of computational materials research is to design all kinds of strange material structures that may not be synthesized in actual situations. It is normal for situations like anisotropy to occur, causing the same material to exhibit two or even more different properties.

"Specifically, what do you mean by specific conditions?"

Faced with this question, Li Yabo showed a bit of embarrassment on his face.

But he still gave a long list of answers like chanting a sutra:

"When preparing samples, a magnetron sputtering coater must be used instead of an electron beam evaporation coater. The argon environment cannot be maintained for too long, no more than half an hour at most. Heat treatment needs to be done in a nitrogen environment, not a vacuum environment. The base material cannot be treated with an ultrasonic cleaner and must be washed by hand..."

"...Oh and, while preparing the periodic carbon array layer, you need to bring a can of iced Coke and drink it all."

Chang Haonan's pen tip suddenly poked a dot of ink on the paper.

"what?"

He thought he heard wrongly.

"Yes."

Li Yabo confirmed very seriously:

"And it has to be Coca-Cola, nothing else."

"..."

Chang Haonan sighed, then nodded helplessly.

He knew that people working in fields like experimental materials science or biology all believed in metaphysics to some extent. Three experiments alone did not have enough sample size and could basically be considered a coincidence.

But anyway, it's nice to provide some emotional value.

Besides, it was just a drink of iced cola, and there was no kneeling or shaman-dancing involved, which was already very respectful of materialism, so I didn't delve into it any further:

"Remember to ask Teacher Liu to reimburse you for the money you spent on Coke in the future..."

After a brief interlude, he picked up the report again.

After all, there are still many doubts that have not been solved:

"Did you synthesize the materials you used for the test yourself according to the process mentioned in the appendix of the report, or did you scrape them from the WS-10G like the one at the Materials Research Institute?"

"It is synthesized by itself..."

Seeing his boss change the subject, Li Yabo finally breathed a sigh of relief and quickly replied:

"In fact, I have done some research on this and found that the reason why Researcher Peng and his team were unable to reproduce the same results using new materials was because they only had an electron beam evaporation coating machine. That's how I discovered the first condition."

Hearing this, Chang Haonan immediately sat up straight and muttered subconsciously:

"Can this turbofan 10G really be buffed?"

Li Yabo was still recalling the details of his previous experiment, so he naturally didn't hear the small voice clearly:

"I'm sorry...what did you say?"

"Oh, nothing."

Chang Haonan shook his head and began to analyze the situation:

"Yabo, have you ever heard of photonic crystals?"

Li Yabo mainly studies metal and carbon-based composite materials, but he is not completely ignorant of the basic concepts in other fields.

"I've heard of it. It seems to be an artificial material with a periodically changing dielectric constant. Due to the Bragg scattering effect, it can selectively control the propagation of light, which is somewhat similar to the propagation ability of electrons in semiconductor materials..."

When he finished talking about this concept, he already understood what Chang Haonan meant:

"You mean, this coating material is a photonic crystal?"

But I immediately began to doubt my own judgment:

"But photonic crystals are basically made of non-metallic materials, and they all have obvious multi-layer structures and traces of human design. This coating material obviously doesn't meet these characteristics, right?"

The so-called "traces of artificial design" is not the same concept as artificial synthesis in the general sense. Instead, it is the addition of artificial basic units on a large scale to form a macroscopic equivalent medium. At least at the current stage, it can be basically considered impossible to mass produce.

Chang Haonan waved his hand:

"This metal-based coating obviously does not have the same macroscopic structure as a photonic crystal, but the arrangement of the microscopic particles may have some similarity in a certain dimension."

"You just mentioned that the sample preparation must be done with a magnetron sputtering coater in order to effectively observe the characteristic emission phenomenon. It is possible that the magnetic field has caused some changes in the microstructure of the material. This can also explain why this material has the same characteristics after being coated on the turbofan 10G by electron beam evaporation."

"In other words, it's not that the projects done by the 606th Institute and the Institute of Aeronautical Materials during the testing process were not comprehensive enough, but that the materials at that time did not have such properties..."

Li Yabo's eyes lit up when he heard this:

"If so, maybe we can try to use methods like the perturbation-dissipation theorem and the Green's function method to calculate the level of thermal emission from a one-dimensional metal-dielectric periodic stacking structure, and then achieve functional design of this... or this type of material at the microscopic level?"

"That's true in principle, but when it comes to the algorithm, a lot of optimization may still be needed."

Chang Haonan replied:

"I will complete this part of the work. You go and verify my other conjecture first."

Li Yabo, who was about to stand up, sat back down:

"You say."

"This material should be coated on the surface of the transition section of the tail nozzle, in other words, under the plasma, but it will still affect the propagation of infrared signals in other directions... This is definitely not something that can be explained simply by low emissivity or strong absorption."

Although Li Yabo also majored in aviation, he had not had much contact with aircraft design since he started studying for his doctorate, so he didn't think about this at all just now.

Now that Chang Haonan reminded him, he finally came to his senses.

"Then you mean..."

Chang Haonan tapped the desktop twice:

"I suspect that this material may have a negative refractive index, which causes the optical propagation path associated with it to be completely different from that of a normal medium..."