Although Li Da’s problem is quite tricky, fortunately, Song Tao has some understanding.

Song Tao replied: "A chemical reaction will inevitably occur between the membrane layer and the gem matrix under high temperature. The reaction mechanisms are diffusion mechanism and chemical bonding mechanism respectively. The color of the coating gemstones in the diffusion mechanism is relatively natural and uniform, and the transition between the membrane layer and the gem itself is more natural than the previous transition..."

Song Tao breathed a sigh of relief after answering.

Li Da gave him almost no time to relieve himself, and then he threw another question over: "Since you said that the membrane layer and the substrate will react chemically, what kind of elements are not prone to diffusion mechanism?"

Song Tao hesitated for a while and said, "It should include iron oxides."

“…”

Just when Song Tao was struggling to deal with Li Da, Zhou Yuanhe quietly came to the corridor of the teaching building.

"Principal Zhou, why are you here?" The court officials in charge of the defense meeting saw Zhou Yuanhe coming here and quickly stood up to greet him.

Usually, Zhou Yuanhe rarely participates in the matter of defending graduation thesis. When these staff members saw Zhou Yuanhe’s sudden arrival, they thought something big had happened.

Zhou Yuanhe waved his hand and signaled them to do whatever they should do: "No big deal, I just come and take a look."

"Which classroom is the fourth defense group for the Gem and Materials Technology major?" Zhou Yuanhe asked.

The field attendant pointed to the classroom directly opposite and said, "The fourth group is there. The main examination classroom is Professor Li Da, and the school leader present is Vice President He Chuan."

Zhou Yuanhe nodded and glanced for a week. He found that there was no Song Tao among the students waiting outside the classroom. So he asked: "Who is the fourth group defending now?"

The field servant quickly looked at the list: "Now it should be the second student named Song Tao."

"I understand." Zhou Yuanhe nodded, and then he signaled to the field servants to take their place again: "I just take a look, you don't have to follow me."

However, the field staff dared not relax. They were afraid that Zhou Yuanhe would find any omissions, so although they took a few steps back, their eyes were still focused on him.

Seeing this, Zhou Yuanhe stopped forcing her and let them follow her.

The defense classrooms in Huachang Dida are all rectangular, with two doors in front and back, and there are glass windows on the doors that can clearly see the indoor situation.

Zhou Yuanhe came to the defense classroom where the fourth group was located and stood still, and looked at the situation inside quietly through the window.

Now Song Tao is concentrating on Li Da’s various tricky problems. If he could see Jiang Zhongtuo, he would definitely think of his class teacher in high school.

In the middle school days of most people, class teachers were serious and responsible. They often lie on the window of the back door to examine the students' performance when the teacher was in class. Once the class teacher found that he was not honest in class, he would inevitably criticize him. Therefore, he was nicknamed by the students as the back door of the death of the head teacher.

However, this phenomenon completely disappeared after college. Song Tao met his class teacher in four years in college and did not add up to twenty times.

At this time, in the classroom, everyone was unaware of Zhou Yuanhe's gaze, and Song Tao's thesis defense was still tense.

Li Da's appearance caught Song Tao off guard. The defense, which he originally thought was easy, became very difficult, so Li Da asked questions in a row where Song Tao did not discuss in detail.

Fortunately, Song Tao was quite prepared. Although some places cannot be explained in a comprehensive way, they can barely deal with it.

In the blink of an eye, the teacher's question, which was originally five minutes, was extended to fifteen minutes.

A female teacher next to her just thought that Li Da wanted to ask Song Tao with high standards, but Li Da was a real professor after all. If he continued to ask this difficulty, no matter how powerful the student was, he would not be able to withstand it.

So she gently touched Li Da's arm, pointed to her watch and reminded: "Teacher Li, it has been more than ten minutes. If you continue at this speed, you may not be able to complete the defense of the other students on time today."

Zhu Sheng also smiled and said, "Old Li, you have asked in depth. The students of Huachang Di University are indeed excellent enough. It is enough for undergraduates to understand the topaz coating technology to this extent."

Zhu Sheng always mistakenly thought that Li Da was showing him the qualities of a college student in Huachangdi, so he focused on asking the first place in gemology, so he gradually began to pick on the questions he asked.

He didn't want to see a student as outstanding as Song Tao in such a dilemma on the stage, so he simply took the initiative to praise the students of Huachang Di University for being excellent enough so that Li Da could quickly move on to the next one.

Li Da frowned. He didn't expect that Song Tao was so prepared. He asked for fifteen minutes but couldn't find out too much of a problem.

Of course, with his knowledge, it is still easy to find Song Tao’s mistakes. If you ask more questions, it may seem tricky and weird, and it may not look good in terms of face.

So Li Da quietly handed a questioning look to He Chuan.

He Chuan pursed his lips slightly, then shook his head slightly, meaning that he would ask Li Da to continue asking.

Li Da nodded, then put on an unspeakable expression: "Song Tao, what you discussed elsewhere is OK, but the research on the issue of coating heat treatment is completely unfathomable."

Song Tao frowned.

Li Da continued: "Let me give an example. What is the difference in the colors of the coated topaz containing metal cobalt at 900℃, 1000℃, and 1050℃? What will the results of different elements? You have not mentioned any of these most critical contents."

"If you don't even take into account such a simple question, then I really don't understand what the significance of your graduation thesis is. It's completely empty and makes me feel very perfunctory and even shoddy."

After saying that, Li Da closed Song Tao's paper and was still on the table casually.

Song Tao was annoyed and couldn't help it. He retorted: "Teacher Li, your reason is a bit far-fetched. I am just defending my undergraduate thesis, not applying for a national science bonus or other defense."

"Please take a closer look at the topic of my thesis, called the current development status of topaz coating technology. It is not a comprehensive study of topaz technology. I don't need to study all aspects of topaz to successfully complete the paper."

"Did a biology student write a paper about the biologic anatomy of hens? You also want to ask him to teach you how to make a pot of hen soup, and then carefully describe what the soup made by the old hen tastes?"

Song Tao spoke out all his doubts like a cannon. Although he still used respectful words in his words, his tone was already very impolite.

Song Tao knew very well that Li Da was deliberately embarrassed because he intervened in promoting the identification of Hetian jade origin and included in the national standard. Thinking of Li Da’s corruption, Song Tao was so angry that he was so angry.

Li Dabing could not help Song Tao, first of all, get angry, so that he could give him enough excuses.

Li Da slammed the table suddenly and scolded: "Song Tao, do you understand what respect for teachers means? I am the chief teacher of your thesis defense. I must be responsible for every student. What is your attitude?"

"I think you don't want to get a degree certificate anymore!"
Chapter completed!