"I've finished learning the textbooks on mechas, but I have fallen behind in monster-related majors!"

Zhang Xiaojiang bowed his head embarrassedly, and his face turned red when he spoke.

In order to be in a hurry, he had to make such a choice, otherwise half a year would not be enough at all.

Lin Feng smiled indifferently, "It's nothing, it's not easy to finish the textbooks of Mecha University in such a short time!" As he spoke, Lin Feng looked at the time: "Now that it's almost time for lunch, come with me to the cafeteria to eat, and test you by the way!" ”

Zhang Xiaojiang looked up at Lin Feng, stunned, and then responded happily: "Okay, Professor Lin!" ”

As the two spoke, they walked towards the company cafeteria, leaving only the bewildered security guard.

When he saw that Lin Feng and Zhang Xiaojiang knew each other, he thought that he would be scolded by Lin Feng or even driven back, but he didn't expect that Lin Feng and the two chatted and ignored him directly.

It's so undignified.

..........

The two had a working meal and sat opposite each other.

The difference is that Lin Feng seems very casual, while Zhang Xiaojiang is quite nervous, the food is placed in front of him, but he is holding chopsticks and holding white rice into his mouth little by little.

Seeing Zhang Xiaojiang's appearance, Lin Feng smiled in his heart, and he didn't delay time.

"Zhang Xiaojiang, since you have finished studying the university textbooks, then I will ask you three questions, and if you answer all of them correctly, I will accept you as a student."

"Okay, Professor Lin, you ask!" Zhang Xiaojiang put down his chopsticks and sat upright, with both nervousness and expectation on his face.

"Hmm!" Lin Feng nodded, and asked casually: "What is the main use of palladium in the process of making mechas?" ”

Palladium, a silvery-white transition metal, is soft, malleable and malleable, and can be forged, calendered and drawn. Similarly, palladium is an indispensable key material in high-tech fields such as aerospace, aviation, navigation, weapons and nuclear energy, as well as in the automotive industry.

In the manufacture of mechas, palladium is also needed, and the amount used is not small.

This question is relatively simple, and Lin Feng did not mean to deliberately embarrass Zhang Xiaojiang.

Sure enough, after hearing this question, Zhang Xiaojiang breathed a long sigh of relief, his straight body relaxed, and replied seriously:

"Palladium is mainly used in gas absorption devices on the periphery of nuclear reactors.

The coolant of the nuclear reactor is water, and under normal circumstances, it will not reach the high temperature that prompts the water to split hydrogen and oxygen, and only when the nuclear reactor fails, such as the failure of the cooling water pump, the heat cannot be dissipated, and the temperature accumulates higher and higher, hydrogen will be produced.

Once this kind of malfunction occurs, then in a closed space, it is easy to produce a hydrogen explosion, which itself is not terrible, but what is terrible is that after blowing up the safety device of the nuclear reactor, radioactive materials are released.

The use of palladium is to prevent hydrogen explosions caused by the decomposition of hydrogen gas due to the failure of the cooling pump, because palladium can absorb hydrogen.

At room temperature, 1 volume of sponge palladium can absorb 900 volumes of hydrogen, and 1 volume of colloidal palladium can absorb 1200 volumes of hydrogen. When heated to 40~50°C, most of the absorbed hydrogen is released. ”

Zhang Xiaojiang explained, Lin Feng nodded, and until Zhang Xiaojiang's answer was over, Lin Feng was still unsatisfied.

"Gone?"

Zhang Xiaojiang was stunned for a moment, thought about it carefully, and continued to answer: "Palladium alloy rolling, can be made into a diaphragm, the thickness of the film is usually 50~100 microns. It is mainly used for the purification of hydrogen.

The principle is the dissolution-diffusion mode, except for hydrogen and its isotopes, no other gas can pass through the palladium film, so the palladium film can be used to obtain ultra-high purity hydrogen. This hydrogen can be used as fuel for rocket thrust in the elbow area of the mech. ”

After Zhang Xiaojiang finished saying the last word, his eyes stared directly at Lin Feng, his cautious appearance was like a student reciting a text in front of the teacher, for fear that the teacher would interrupt him and bring up the mistakes in the recitation process. ”

After listening to Zhang Xiaojiang's narration, Lin Feng did not nod this time, but asked, "What else?" ”

"And!" Hearing this, Zhang Xiaojiang's heart suddenly tightened, he carefully filtered his mind, filtered all the knowledge points about the element palladium, but he never found more answers.

In just a dozen seconds, Zhang Xiaojiang, who was cramped and uneasy, was so anxious that dense fine sweat began to appear on his forehead.

"Remind you, in the small print note in the lower right corner of page 183 of the freshman "Mecha Materials Science"!"

Mecha Materials, p. 183.....

Zhang Xiaojiang tried hard to recall the content of "Mecha Materials Science", and his frowning brows were loosened for a long time.

If it is changed to ordinary people, Lin Feng's reminder is equivalent to nonsense, who reads books and remembers page numbers.

However, it is very necessary for an apprentice who wants to learn mecha manufacturing, and Lin Feng not only reminded Zhang Xiaojiang in this way, but also tested his carefulness in learning.

If you want to learn to build mechas, you must be bold and careful.

183 pages..... 183 pages.....

Zhang Xiaojiang was so anxious that he was sweating profusely, filtering the knowledge points in his mind over and over again, and finally, he had a flash of inspiration and couldn't wait to answer:

"It's a palladium-iridium alloy, which can significantly improve the corrosion resistance of Pd, and the palladium-iridium alloy is used as an electrical contact point."

Hearing this answer, Lin Feng nodded with satisfaction and added:

"Palladium alloys are highly resistant to corrosion.

Palladium-gold alloy, more than 20% gold is insoluble in nitric acid.

Palladium-silver alloy, with a silver element content of less than 50%, has a corrosion resistance close to palladium, while Pd-Ag alloy containing 50% silver and 10% platinum or gold can be used to make corrosion-resistant parts and cases for optical instruments in mecha.

Palladium-iridium alloy is used as a special electrical contact point in various circuits of mechas. ”

Zhang Xiaojiang nodded again and again, but he was very puzzled in his heart, because he remembered that in the textbook, there seemed to be no mention of Pd-Ag alloy.

As if seeing through Zhang Xiaojiang's doubts, Lin Feng smiled and said, "I didn't write Pd-Ag alloy in the textbook, only palladium-iridium alloy. ”

No wonder!

Zhang Xiaojiang was relieved, and then silently took out his notebook and wrote down the new knowledge points that Lin Feng had just mentioned.

Lin Feng admires Zhang Xiaojiang's attitude, a good memory is not as good as a bad pen, since he does not have the ability to remember, taking notes is a good choice.

After Zhang Xiaojiang finished remembering, Lin Feng asked his second question.

"What are the mechanical mechanics of the mecha's legs?"

The mecha is a kind of machine that fully embodies the mechanical formulas, and every action of it is accompanied by the calculation and application of thousands of mechanical formulas.

Of course, the number of mechanical formulas applied is different for different organs and parts, and the most common part is the arm.

There are more than 1,000 ways of human arm movements, and when you change to a mecha, there are only 388 kinds of arm movements left, and each arm movement can extend dozens or even hundreds of mechanical formulas.

Including every piece of mechanical muscle of the arm, mechanical power, mechanical torque, and so on.

Compared to the mecha arm, there are only 55 ways to move the mecha legs.

If it is converted, there are hundreds or thousands of mechanical formulas covered by the movement of the mecha's legs.

Of course, there are many overlapping mechanical formulas, and excluding these repetitions, there is not much left.

Even so, it is very difficult for a college student to explain these mechanical formulas.