Pre-review
In the last issue, we introduced the research of graphene on the flexible screen of mobile phones to achieve the effect of free folding of mobile phones. The solar cell light panels use nanotexturing technology to improve the utilization of light energy, and a few single-layer graphene films are stacked together for application. The field of the throat, and then explore the structural characteristics of graphene under the scanning electron microscope of the SIGMA 500 field emission. In this issue, we will change the topic and talk about those things in August.
Preface
Let's talk about a recent big release. On July 27th, at 20:01, the movie "Wolf Wolf 2" was officially released nationwide. It was released in 4 hours and broke through 100 million yuan. The attendance rate was as high as 59.1%. Domestic film record. Over 300 yuan a day at the box office for two days on weekends. As a pseudo-military fan, Xiaobian also took a look at the heat and joined the army of the weekend cinema. It was really bloody after reading it. However, did you notice a small detail, the bullet on Wu’s neck, this one Throughout the bullets, the audience created a very good suspense, suffocating the appetite of the audience, step by step, is a classic, Xiaobian also wants to study the bullet, the material, properties, texture, performance, etc. of the bullet, but the bullet 岂It is a small editor of this ordinary person, then let's take a look at the bullet casing.
First, sample processing
After the gun was fired, a large amount of gunpowder burned, so there was a lot of smoke marks on the shell, and the number of the electric spark was blocked, and it was more difficult to clean after soaking in ethanol. The small series uses the cotton yarn to apply the gun oil, and immediately wipes the shell after the shooting, and the smoke is quickly removed. After wiping, the cartridge is ultrasonically cleaned in acetone for about 10 minutes, then the shell is removed and dried, and then rinsed in absolute ethanol.
Second, different models of shell images and matching gun type
The caps of the above-mentioned shells are from the left to the right, 92-type pistols, 54-type pistols, 56-type submachine guns, and 95-type automatic rifles. The 54-type pistol uses a 7.62mm bullet. The 54-type pistol has the characteristics of small size, light weight, easy to carry, limited by the terrain environment, and quick response. It is easy to cover the enemy in a narrow space.
The Type 92 pistol was developed to replace the 54-type pistol of the original equipment. The QSZ92 semi-automatic pistol is divided into two sizes: 5.8mm and 9mm. The shell size in the figure is 5.8mm small diameter.
The Chinese Type 56 submachine gun is the Chinese version of the Soviet AK-47 assault rifle. The official name is the 1956 submachine gun. In the 1980s, it was replaced by the 81-type automatic rifle. Launched a 7.62X39mm56 rifle.
The Type 95 automatic rifle is an assault rifle developed by the China Ordnance Equipment Group Corporation 208 Research Institute, with a diameter of 5.8mm. It is the second small-caliber rifle developed in China.
Third, the shell under the scanning electron microscope
Figure 1 Surface shape of a 54-type pistol, a 92-type pistol, a 56-type rifle, and a 95-type automatic rifle
Fig. 1 is an image of 20,000 times of the surface of four kinds of shells obtained by electron microscopy. The middle part of the shell is taken separately. It can be seen that the unevenness is generated, and the debris is generated because some debris adheres to the surface of the shell after the gunpowder is emitted. By performing energy spectrum analysis on a typical sample, two locations are taken. The statistical results are shown in Table 1. We found that the main component of the Type 56 rifle is copper, and two components such as aluminum, silicon, sodium, iron and chlorine appear. In the past, the bullet shells were made of brass. Most of them are made of steel alloy materials. The ductility of copper is good, it is easy to stretch and form during manufacturing, and it has a certain strength. The bullets are more airtight when launched. Shelling is easier, and the mechanical wear of the gun is low, so it is the first choice for making the shell. However, some countries that lack copper resources but need a large number of troops are replaced by other materials, such as cheaper steel or steel alloys, and then a layer of copper is attached to the surface, so the results of Table 1 appear, one surface is intact. With copper coating protection, the two surfaces are damaged, revealing internal components, and the shell is left for a long time, and a layer of patina will appear on the surface.
Table 1 Different types of components of the 56-type rifle (mass fraction, wt%)
Type 56 rifle 1 2
C 8.11 14.34
O 2.71 8.65
Al —
0.72
Si — 0.7
Na — 0.6
Cl — 0.68
Fe — 1.09
Cu 89.18 75.68
During the scanning of the photo, we found cracks in the closing of the shell. We chose one of the most cracked shells, as shown in Figure 2, Type 95 automatic rifle. We found that the crack extended axially toward the inside of the metal.
Fig. 2 Crack appearance of the outer surface of the 95-type automatic rifle shell
postscript
The crack of the shell develops into the interior of the metal, which may cause sudden damage to the metal structure, destroying the integrity of the shell, and the internal ammunition is prone to leakage, so it can have extremely serious consequences in the process of transportation, storage and blasting, so Analysis and discussion of such cases has certain engineering application value. If you want to find out the cause of the cracking of the shell, then follow the pace of ZEISS scanning electron microscope and explore together!
On the 90th anniversary of the founding of the Chinese People's Liberation Army
I would like to extend my festive congratulations and cordial condolences to the great soldiers!
What's the highlight of the next issue? Stay tuned!
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