Columns

2017-02-03 Sorry for the late arrival of allightec - #5.Graphene lubricants already have mass production technology.
Graphene oil in fact as early as 2014 / July has been to MN / LN base oil to complete the sample, but after all, not a commercially available commodity, had to wait until the manufacturers really need to come back, had to know the lubrication effect is great, see Square graphene oil published one after another, but did not dare to provide test information also negative call negative. Please see: https: //zhuanlan.zhihu.com/p/20608773
 
 
Figure 1, the customer to provide synthetic oil and additives. (in front of the golden yellow liquid)
b1
 
First look at the last time to base oil test data. In 2014, we infiltrated the base oil with a diafiltration threshold of 0.5 wt% and 1.0 wt%, and tested it simply after 10 minutes of turbulence. LN base oil friction coefficient of 0.13. Test method load 20N, grinding time 60min, the grinding ball ZrO2 and the number of grinding 57,600 times and found:
1. There is no precipitation and dispersibility of graphene-based lubricants.
2. Friction coefficient of 0.08858, the friction weight loss of 0.00015 grams. Lubrication efficiency increased by 93.8%. 

b2

b3

 

According to the relevant literature, we improved the direction of the follow-up sample:
1. The number of layers is less than 5 layers, preferably 3 layers.
2. Filament diameter of 20 microns can be extended to 100 microns horizontal scale.
3. The diafiltration threshold is reduced to 0.01 ~ 0.05%.
But this time (1) and (2) too late to do this graphene, but from the test data show that the direction is right.
We look directly at the test data. Figure 3 shows the performance of the original synthetic oil by adding 1 wt% of the additive to the friction coefficient and wear loss.

b4

Figure 4 shows the performance of the gravitational scale and wear weight loss of the gravimetric 5 micron multi-layer graphene.

b5

Figure 5 shows the performance of the gravitational scale and wear weight loss of 10 micron multi-layer graphene in transverse scale.

b6

Figure 6 shows the performance of the transverse scale of 20 microns of graphene at the friction coefficient and wear loss.

b7

Finally, I sorted out the summary table (Figure 7).

b8

The conclusion is that the wear test is a high standard passed, but whether it is going through carbon deposition test and road test, after the holiday with the customer to confirm the follow-up, but can ensure that graphene oil can be published soon, the first quarter of next year Zhiyang will be published with many other graphene products to the world.

more
2017-02-03 Sorry for the late arrival of allightec - #4.The graphene coaxial cable will be developed towards cost-effective technology.
Coaxial cable as early as 2015 ╱ November has been completed on the sample, until this week to Jiangxi back to the original sample was to try to sort out the previous development experience. Please see: https: //zhuanlan.zhihu.com/p/20113838.

Figure 1, graphene conductive ink - coaxial cable
c1

We use the graphene conductive ink to do the second application, that is, high conductivity of graphene ink instead of copper, hoping to use a smaller diameter, lower cost to achieve higher physical properties. The current sample stage per kilogram cost less than 380 yuan of conductive ink to estimate the future mass production per square meter cost of 1.5 yuan or less; the other hand, coaxial cable within the weaving network according to the material is generally copper or aluminum Metal wire mesh of the conductive material, the number of network cable 64 or 128 series, the higher the shielding rate, the less the interference between the signal. Figure 2 shows the difference between a conventional cable and a graphene cable.

c2

c3

 

It can be seen that the difference between the two points in the graphene coating to replace the metal isolation network (copper).

 

The main purpose of the coaxial cable is to transmit the signal, the pursuit of the ultimate goal should be the signal completely intact transmission, not due to wire material and structure itself caused by signal loss or distortion caused by sound staining. So the resistance of the wire itself and the capacitive resistance and equipment to form a good match between the signal to be 100% transmission. In addition, the rapid development of today's society, daily life on the electrical and electronic equipment, a higher dependence on a variety of electrical equipment, electromagnetic radiation generated by the work is full of our living space, if the wire itself, radiation shielding effect is poor, These electromagnetic interference, radio frequency interference and other noise may interfere with the normal audio and video signals, resulting in signal to noise degradation phenomenon, which is not the wire users are happy to see the results.

 

Electrical equipment in the course of work, in addition to the interference from the outside, but also subject to various interference from the inside. Therefore, for the anti-interference of electrical equipment, it is necessary to suppress external interference, but also as much as possible to reduce the internal interference caused by the adverse effects of equipment. Internal interference can be divided into two categories, one is the internal noise, the other is the internal electromagnetic and electrostatic interference. Internal noise is due to the various internal components produced by the "thermal noise", "powder noise" and "contact noise." And the internal electromagnetic and electrostatic interference is due to the internal arrangement of various components caused by the electric field induction, magnetic field induced interference.
Electric field sensing is an interference caused by the coupling of the electric field, also known as "capacitive coupling interference", which is due to the existence of distributed capacitance between the two units of the circuit is the result of the interaction between the two circuits. As the actual circuit in the presence of stray capacitance, which is bound to make a circuit charge changes affect the other circuit, the formation of the interaction between the two circuits. In the extremely high frequency of the radio frequency band, the electric field coupling interference is extremely serious, in the low frequency if the working level of the circuit is not high, even in the audio range, the electric field coupling interference can not be ignored.

 

Magnetic field sensing is a kind of interference caused by the coupling of the magnetic field, also known as "inductive coupling interference", which is due to the inter-circuit (or between the circuit) between the magnetic induction coupling caused by the magnetic field interaction results, also known as For mutual inductance coupling, when there is mutual inductance between the two circuits (circuits), the change in current in a circuit will be coupled to another circuit in the form of a magnetic field.

 

To suppress the interference caused by the coupling of the electric field, it is necessary to take corresponding measures to reduce the stray capacitance and the distributed capacitance as much as possible to reduce the interference caused by the electric field coupling. The concrete measures are as follows: electric field mask, wiring and layout. The mask of the magnetic field can take the following measures: the use of high permeability materials made of the mask, to reduce the loop area of the protected circuit and mask magnetic field interference source.

 

Graphene serves as an electric field mask. We use the previously developed conductive ink coated in the conductor after the package, even more than the original use of copper foil and silver copper braid double-layer mask effect is even better five times, if not the industry standard must have woven network, we think that can Completely replaced by graphene conductive ink, even if the original structure to retain the weaving density, the operator deduced the cost of less 2/3.

 

Let's look at the test data. This project took the researchers to do four days to complete. The original data shown in Figure 3.

c4

Refresh the test data as shown in Figure 4. Coaxial cable is susceptible to interference from the external environment, so choose nine environment-related frequencies to do the test, but we are more concerned about 1.8 ╱ 1.9GHz, because this is the main channel of the current mobile phone.

c5

There are two conclusions:
# 1. The core plus graphene than the core without graphene at high frequency 1.8GHZ and 1.9GHZ attenuation significantly improved;
# 2. The core plus graphene rocking rupture test 12000 times, the test results in 2.4GHZ attenuation significantly increased.

 

This reminds me of yesterday to see a news: China developed the first international graphene low noise amplifier monolithic integrated circuit. The implication of graphene at room temperature carrier mobility is 4,300 cm2 / V · s. For the two-dimensional graphene materials susceptible to damage and pollution characteristics, independent research and development of the pre-deposition protective layer of low damage, self-alignment process, in 2013 to achieve the highest international oscillation frequency of graphene crystal, 2015, graphene materials and Device technology continues to improve, graphene field effect transistor cutoff frequency fT to 407GHz, SiC substrate epitaxial graphene crystal of the highest international standards.

 

Recently, in the graphene amplifier monolithic circuit design and circuit key technology breakthrough, successfully developed the first international graphene low noise amplifier monolithic integrated circuit, in the field of graphene RF caused a strong shock. The circuit operates in the Ku-band with a center frequency of 14.3 GHz, a maximum gain of 3.4 dB, and a minimum noise figure of 6.2 dB.

 

I think this project is also based on the same principle, if the amplifier monolithic circuit has been found routines, my next project should be graphene diaphragm. This means that the first graphene headset has been a little tricky.

more
2017-02-03 Sorry for the late arrival of allightec - #3.Graphene conductive nylon has been able to do metal-like conductive.
Conductive nylon (PA6) I have been in the 2014 ╱ 08/27 has been 3 to 5 wt.% To complete the development of anti-static masterbatch, then no customers can send samples have been put now.

Figure 1, 3 wt% graphene / PA6 composite - antistatic plastic.
n1

Figure 2, 5 wt% graphene / PA6 composite - antistatic plastic.

n2

 

These two days thought to go to Changzhou speech and published several success for the customer development of graphene products, think about the factory to help me increase the weight try, had to do thermal conductivity of PA masterbatch, and other thermal conductivity test Of the gap, we first tested the chip resistance, the magic of the things there.


Figure 3, 10 wt% graphene / PA6 composite - static dissipative (ESD) plastic.

n3

 

Figure 4, 15 wt% graphene / PA6 composite - conductive and EMI shielding plastic.

n4

Originally to do 20wt% of the test piece, but found that the high permeability filter threshold, the material does not go, the extruder can not eat the material, resulting in insufficient melting strength, only to wait for me to come back after the factory to find a solution.
 
 
When good luck to find you on the time, is the walls are stalls can not file! Recently, in order to sample the anti-shielded wire, from the masterbatch factory was found in Taiwan Taoyuan a home to help the car factory manufacturing functional masterbatch professional boss, I told my thoughts, I said 15wt% if you can do chip resistance up 104Ω / □, then the higher the diafiltration threshold can not be conductive! He actually answered me he could have been kneaded to 40wt%. I know that my technical threshold has improved!
 
 
He also mentioned the use of several mainland and Taiwan's graphene material, to the effect of less than conductive carbon black, to slightly better than the conductive carbon black but the price is astronomical, simply can not be commercialized! This is entirely within my expectation, I immediately provided three horizontal scales of different layers of graphene to his kneading, conductivity has been raised to 7.4Ω / □, is sealed into coaxial cable for subsequent anti-shield test.
 
1484297682968 copy
more
2016-07-26 Sorry for the late arrival of allightec - #2. Graphene barrier film already has a production level.
These days seems to wait for the college entrance examination results to put the list, know that they will be admitted to the first volunteer, but always have to see the results to be accurate. Finally with graphene acrylic ink coated in the PE film of oxygen permeability penetration news, as the second solution of the barrier film (graphene join LLDPE masterbatch film) test data will wait for me to come back from Changzhou again to announce, but I am still proud to announce: Allightec to help Chinese enterprises to develop the second paragraph of graphene application products can already come out.
 
 
This project started earlier than the thermal powder coating, it is not the production process is more complex, but the processing scale out of a problem, the results took me 2 months time. Even if I produced the cost of graphene is very cheap, but a test can not reach the standard, the bulk material should be lost; the previous powder coating okay, each batch of production as long as 2 kg, plus 5 ~ 10 wt% Molecular money, and had asked Changzhou co-manufacturers only send polyester and epoxy resin 5 kg, but also because we have in front of the solvent-based paint to master the correct diafiltration threshold. The other hand, the block of the film a batch of dozens of kilograms to hundreds of kilograms, no R & D test machine can be used, really makes me a headache.

 

The Chinese people are flexible and smart, I think this kind of process is more like blow molding or pull film, since I help the adhesive barrier to the factory too few can not do, I think RMB.500 to find their own factory plastic bags factory asked, Fortunately, the factory owner willing to help me. The solution is to use their raw materials, the middle of the two proportions of LLDPE masterbatch, followed by their mother particles to push, but also said that not sure will be successful. Because graphene is black will pollute the die, so accept the above costs. This is what I call: in Taiwan radius of 100 km within the cluster of various processing plants, coupled with the boss is very hearty, so I can soon be effective.
 
 
The barrier film is used in the vacuum insulation board, I discuss with the Bengbu customers on 4/13/2016 to know that this is what we often see the vacuum packaging bags, but blocking the water, the requirements of higher oxygen, reaching 0.05 cc / m2. Day, while the traditional food packaging is required only WVTR (water vapor transmission rate) of about 102 g / m2. Day, OTR (oxygen permeability) of about 102 cc / m2. Day.

 

In the mechanism of barrier properties, it is considered that in the polymer solution / dispersion system, the nanoparticles are finely dispersed (insertable / sandwich type) graphene. When the nanoparticles are stacked and arranged on top of the flexible film substrate, a "meandering circuit" form creates a hindrance to the gas. As shown in Fig. 1, the nanoparticles move from the aggregated clay to the nanocomposite (intercalated) coating. As long as d2 distance is greater than d1, there is a curved path, the oxygen barrier performance than the unmodified polymer matrix has improved.

1 copy copy copy copy copy copy copy

 

Looking back, the "vacuum lamination bag" is made up of four composite films, which can usually be divided into outer layer, barrier layer and inner layer. The typical laminated structure shown in Figure 2 can be expressed as polyester / nylon / aluminum foil / polyethylene.

2 copy copy copy copy copy copy

 

1. Polyester film PET, also known as two-way (or biaxial) stretch polyester film PET often used as aluminum foil bag outer material, commonly used thickness of 12μm. It has high melting point, high heat resistance, high mechanical strength, high rigidity, high transparency, high resistance to fragrance, high gas barrier characteristics, and because of its molecular structure in the polarity of the relationship between the surface tension is high, slightly corona After treatment, the surface tension of up to 52 mN / m, the printing and bonding are very favorable. When PET is used as the outer material and other heat-sealable materials (CPP, PE, etc.) composite heat sealing bag, even if the temperature up to 220 ℃, it will not melt deformation, not sticky knife, is conducive to composite film Bag making.

2. Nylon film PA commonly used thickness of 15μm, can be used for the manufacture of anti-puncture performance, large-capacity heavy-duty bags, often used in the inner layer of PE similar to the sandwich, such as PET ╱ AL ╱ PA ╱ PE. Nylon film also has a high melting point, high heat resistance, high mechanical strength, high transparency and excellent puncture resistance performance, its rigidity and barrier than PET poor, relatively soft, excellent texture of the hand can be applied to vacuum bags, Cooking bags and so on.
 
3. Aluminum foil AL is a metallic material with complete moisture resistance, gas barrier and light resistance. If there is no mechanical damage and pinholes, it is completely impermeable to moisture, airtight (O2, N2, CO2, etc.) Light, with high heat resistance and oil resistance, so, made of aluminum foil composite bag, with a full seal, high security incense, high oil resistance, high temperature and other excellent performance, is the most high-end composite flexible packaging materials.


4. Polyethylene PE is often used as aluminum foil bag inner layer material, has a good heat sealing performance. PE has excellent low temperature resistance (the lowest temperature of up to -70 ~ -100 ℃), chemical stability, and resistance to the erosion of most of the acid (intolerant acid). Figure 3 is the general plastic water resistance / oxygen permeability.

3 copy copy copy copy copy copy

 

"Vacuum laminated bag" thickness: 70 to 180 microns, the role of each layer:
PET - high mechanical strength, good printing (usually without surface treatment);
AL - barrier strong, opaque;
PA - soft, excellent puncture resistance;
PE - ordinary packaging inner layer for heat sealing.

 

Therefore, I decided to keep AL and PE, that is, to retain the best barrier to AL, PE plasticity easy to vacuum process. Figure 4 shows the acrylic ink coated on the PE film 1/2/3 layers, and then bonded aluminum foil.

4 copy copy copy copy copy copy

 

Then, we first conducted oxygen permeability test, found 1/2/3 layer of oxygen permeability were: 1.93 ╱ 2.24 ╱ 2.22 cc / m2. Day, we think it is caused by uneven coating.

5 copy copy copy copy

6 copy copy copy copy

7 copy

 

Then, before we have not got the official finished product test data, we according to the "multi-layer composite barrier" formula: 1 ╱ P = T1 ╱ P1 + T2 ╱ P2 + T3 ╱ P3 +
T1, T2 - the thickness of each composite layer; P1, P2 - the transmittance of each composite layer

 

The original four-layer vacuum laminated bag: 1 ╱ P = (15 ╱ 1) + (12 ╱ 8) + (15 ╱ 200) + (15 ╱ 4800)
Therefore, P = 0.06 cc / m2. Day
New scheme: 1 ╱P = (15 ╱ 1) + (135 ╱ 2) = 0.01 cc ╱ m2. Day
 

In theory, the more layers, the thicker, the better the barrier, and we use the graphene coating not only can be reduced to 2 layers, the cost is lower, and the oxygen permeability is better than the original 4 layers. It is clear that the oxygen film permeability of the PE film from the original 4,800 cc / m2. Day down to 2 cc / m2. Day, to prove the excellent graphene barrier properties.

  

Assess the gas barrier and moisture resistance of the encapsulated material we can use Water Vapor Transmission (WVTR) and Oxygen Transmission Rate (OTR) as the index, the application of various types of industrial applications ask for as follows:
◎ food packaging WVTR about 102 g / m2. Day, OTR about 102 cc / m2. Day;
◎ Inorganic solar cell package WVTR about 10-1 g / m2. Day, OTR about 101 cc / m2. Day;
◎ LCD display package WVTR about 10-2 g / m2. Day, OTR about 101 cc / m2. Day;
◎ organic solar cell package WVTR about 10-5 g / m2. Day, OTR about 10-4 cc / m2. Day;
◎ OLED display package WVTR about 10-6 g / m2. Day, OTR about 10-6 cc / m2. Day.
 
 
For carrying out this project, so I found graphene barrier film there is a lot of room for it.
more
2016-07-25 Sorry for the late arrival of allightec - #1. Graphene powder cooling coating has been violated principles.
If you have not seen the polymer coating can reach such a high thermal conductivity, it can now let you feast for the eyes, my guidance professor on this issue of my hair, I still do basic representation of information. Make up the In-plane thermal conductivity: yes, that is 52 W ╱ m * K.
 
 
I am proud of having so much material, I think about the thermal resistance formula: R = L ╱ K, that is, the smaller the film thickness, then the smaller R results the bigger K. The first spray thickness of 100 to 120 microns, this time I come to challenge the minimum film thickness, perhaps limited by multi-layer graphene and horizontal scale of 5 microns under the constraints of the coating can only reach more than 40 microns thick.

 

Then we use Hot Disk TPS2500S, TPS method is not only suitable for measuring all kinds of homogeneous materials and non-directional coaxial structural materials, from low thermal conductivity material to high thermal conductivity of metal materials can also be tested, the amount of material can be measured simultaneously Thermal Conductivity, thermal diffusion, heat capacity, can be divided into many test modules according to the application, can analyze the block, film, sheet high thermal conductivity and different direction of the material, can also be analyzed for different types of samples: liquid Shape, paste, gel, powder and other samples of heat transfer coefficient.

11 copy copy copy

 

At present, Hot Disk TPS test method, has been able to test a variety of generally can not test the heat conduction of materials (such as: nano-aqueous solution, polymer film and other special materials), and can be measured simultaneously X, Y axis direction and Z Axial direction of the isotropic thermal conduction test. Here is the test data we get on the Z axis.

12 copy copy

 

Yes, the thermal conductivity is surprisingly high. But the high thermal conductivity and some of the contribution of aluminum, we follow the thermal resistance formula: R = R1 + R2 = L1 ╱ K1 + L2 ╱ K2, followed by the formula into: 140 ╱ 148.1 = 40 ╱ K1 + 1000 ╱ 237, then K1 = 14.3 W ╱ m * K, once again to break the record.
 
 
Now the heart is still very excited. With most of China's graphene enterprises, I am a source of science and technology from the people who have to say from their own words to bear, not to mention I decided to come forward to judge the current chaos in the country. Append this field test is temporary, I would like to help me deal with the powder coating factory with their existing thermal test bench to help me see this graphene heat powder coating what ability, the results made me feel shocked, even down 27 ℃, the first time put the good news to share to you. If you were in Changzhou at the end of June, maybe you could have asked me to publish three products that included paint.

 

First of all, this test platform is intuitive, as the paint industry itself said that China does not have a standard test method, but everyone can accept this result at a glance. We placed the graphene coating on the aluminum plate on the left side of the heating plate, and the right side of the original is not coated aluminum plate as the control group. We measured the temperature of the hot plate directly, rather than the temperature of the coated aluminum plate.

13 copy

 

Then, we adjusted the power to 8W, the control of the right side of the temperature of 72.6 ℃, while the left temperature of 61.2 ℃, in other words, the aluminum plate by polystyrene cooling coating cooling 11.4 ℃.

14 copy copy

 

At this time I think the whole heat management is the first conduction, followed by convection and radiation, which radiation is much faster than convection. So I continued to adjust the power to 16W, the results of the shock occurred.

15 copy copy

 

The right side temperature is 118.0 ℃ and the left side temperature is 90.8 ° C. In other words, the aluminum plate is cooled by 27.2 ℃ by graphene heat dissipation coating. Frankly speaking, this is the first time I have tried to do graphene powder coating, not very satisfied with the thermal conductivity, but I can announce here: the world's first "real" can be commercialized graphene products completed by the Allightec, how could I not be excited?

 

The story begins 18 months earlier, because the Jiangxi investors can not provide the original commitment to continue the research of graphene, but Allightec currently has more than 200 kinds of graphene materials, and More than 50 kinds of application technology had been completed in September 2014. So I often say that China itself wasted such a long time. In contrast, China appear a lot of "graphene concept stocks" since 2014, after which there have been a lot of speculation is the product of graphene, otherwise you have long been heard by grapefruit consumers to accept the positive news, which is indeed the industrialization of graphene is not healthy.

 

In fact, my heart is not only anxious, more of the heart of the "bitter". Over the past two years ran nearly 20 provinces in China, see also a lot of state-level by the district's leadership, even if I bring samples are dubious, is asking me to do with the local business docking. Even worse, as long as I go to invest, but even the docking business is nothing but a window contact Bale, because the other did not have the right to decide, and even the company has no large-scale research and development capabilities, simply can not go on.
In this sinking day I chose to publish the graphene-related articles in the "zhihu", because I knew that the concept of graphene was always separated by a layer of yarn due to the deviations of many scholars and practitioners. The last six months, because my college students to support some of the funds, so to reduce my economic pressure, but the real reversal of this dilemma is an angel fund in Shenzhen to introduce this project. You may have seen me in front of the article will be curious, criticized the graphene pseudo-science I have named, but these good friends are "do more hard work" people, I chose not to name and units to write out.

 

Probably in April 2016, the fund manager told me that they are ready to survey some graphene enterprises, I based on correcting graphen industry mentality to tell him a few views:
1. Declare an annual output of several million tons, but have no "real" mature application of goods, just "make money";
2. the establishment of graphene company for more than 5 years but still buy powder or suspension, it seems that is not saved;
3. Only graphene application technology but they do not have graphene material is in vain.
He heard it also makes sense, then he proposed Allightec simply to help them, so put my wechat to the CEO of the enterprise, we contacted, it learned that China's graphese industrialization really encountered a "bottleneck". This phenomenon can be proved from two angles, first, the graphene industrial park is China's first to become a national "holy land", regardless of the government and private enterprises into how much money into, but more than 50 enterprises only two to leave the incubator can Into the product business phase; second, this business is one of the two, the use of local graphene 2 years has been unable to break through the technical per gram of graphene 300 yuan to make the thermal conductivity of powder coating 0.2 to 0.4.

 

I used to speak to their company in mid-May to understand their two companies, the two executives are very frank to say that there are orders, but the technology can not break through and the problem of high costs and distress. In fact, at first I thought it was solvent-based paint, we also do thermal conductivity higher than 10 ready-made graphene products. A scene to find the powder coating, the idea of ​​a turn two "thermal" mechanism is the same, even the polymer is also mostly used polyester or epoxy resin, in the past development experience is to find the interface and leveling relationship. But in order not to break through the cowhide, I only promise to be able to do thermal conductivity 5 or more, and even directly with each other's customers directly look at the heat transfer path, this is difficult for Chinese enterprises to do so, so I decided to help them one.
We agreed to use their existing resin to verify the future for mass production into a seamless, which in the customs clearance to Taiwan when delaying a little time, but after two weeks I began to conceive the writing of this series of articles, officially announced with you graphene The era really came. How to say? We used three days to the graphene sent to the factory mix, spent some time to do thermal conductivity test, the results of thermal conductivity up to 12.75, really higher than the expected level of both sides are much higher.

 

No information is not true. First, the thermal conductivity test, the heating power of 12W, the use of refrigeration chips as a temperature difference to measure in-plane thermal conductivity. Place the sample between the heat sink and the heat source. See Figure 1,2.

16 copy copy

161

It is clear that we have found two graphene powder coatings with two solvent-based coatings (this sample), the thermal conductivity is higher than 10. See Figure 3.

17 copy

 

The temperature curve of the sample after heating is shown in Fig 4.

18 copy

 

But this is still not clear how much the temperature of this product can be reduced, we added a physical test and found that 120 ℃ heating conditions, the aluminum plate through the convection and its thermal conductivity of 210 W / m * K conditions, the temperature dropped to 56.9 ℃ The But the addition of graphene powder coating and further reduced by 20 ℃. See Figure 5.

19 copy

 

We routinely calculate the theory. According to heat conduction formula: K = Q * L ╱ △ T. (1000 + 100) ╱ 12.75 = 100 ╱ Kcom + 1000 ╱ 201; K = 12.75 W ╱ m * K, the thickness of 1000 μm, K = 201 W ╱ m * K, graphene powder coating: Kcom = 1.23, that is, the actual thermal conductivity of graphene powder coating is only 1.23, but if you look back to the original business of this enterprise plus graphene thermal conductivity of only 0.4, then Kcom '= 0.00363, increased by 338.8 times , Enough cattle it.

 

The light that their technical strength is not a hero, if I told the original thermal paint per kilogram to buy you 15,000 yuan (yes, you did not wrong, but the thermal conductivity of only 0.4), and now I tell you the cost of Allightec is RMB 20 * 95% + 200 * 5% = $ 29, if you are in this industry will be tense, not to mention I have done in the thermal conductivity of more than 12, and the diafiltration threshold can also be added, I recommend to more than 20 Not a problem. How to say? Heat conduction is thinner the better, so the film thickness to be reduced, to reduce the film thickness from the particle size to proceed, and the smaller the particle size, theoretically more complete lattice vibration, thermal conductivity will be better. There is also a discovery that graphene is close to the "black body" of the material, the heat emissivity even more than 95%, while the radiation than the conduction speed faster, so the cooling effect will be better is the inevitable truth.

more
2016-07-24 Going to the bottom of the matter.-#25. Where is the graphene surface wave detection technology so amazing?

After reading this article I understand the mystery. In fact, I will use the project with the college group to offer sb. favours at the expense of another, which is understandable, but to say "will lead the sensor technology revolution", which is recently published with their lithium-ion rechargeable no.5 batteries, the development of the whole graphene will eventually be a flash in the pan. Ref .: Nature Communications 8, Article number: 14579 (2017) | DOI: 10.1038 / ncomms14579

 

First, Lin et al. (2015) developed a method for converting polyimide (PI) into a porous graphene membrane by a one-step process. The method is further applied to the development of supercapacitor energy storage devices and flexible strain sensors. The use of laser-induced graphene (LIG) for high thermal conductivity and low heat capacity is ideal for thermal sound sources. In addition, the porous structure will be sensitive to weak vibration response, which is suitable for sound detection. Therefore, a simple one-step manufacturing will be suitable for the realization of this new type of artificial throat.

 

Tsinghua University Tian-Ling Ren through the direct laser writing PI development step, can wear and low cost LIG artificial throat, it is in the generation and detection of sound to show good performance. Compared to conventional acoustic transducers, this LIG artificial throat has a completely different working mechanism, which typically utilizes piezoelectric and inverse piezoelectric effects. When working as a sound source, the LIG artificial throat can produce a wide frequency sound from 100Hz to 40kHz. The thinner LIG will produce a higher sound pressure level (SPL). When working as a sound detector, the LIG artificial throat shows a unique response to different types of sound and throat vibrations. LIG can recognize coughs, buzzing and screaming with different tones and volumes. In addition, it has the ability to identify words and sentences. Benefiting from its ability to produce and detect sound, the wisdom of LIG artificial throat will significantly illustrate the disabled. The throat vibrations with different volumes and frequencies can be converted into controllable and pre-designed sounds.

 

This is really not SERS technology, but rather intuitive to identify different tone and volume changes, through the conversion into a controllable and pre-designed sound. But there are two misunderstandings, first, usually from academic to business to go through a long time, and this technology is novel but the threshold is low, that will lead the revolution is the businessman exaggerated the argument. Secondly, this technology to establish a variety of ethnic databases, back-end need sufficient funds and a large number of research institutions investment. However, if you can go to mass production, after all, do not like Stephen Hawking but also with the "eye movement" so hard that is sure to bring deaf and mute the gospel.

 

v2 d0a0b90cd46c5a0551d465b843faeb8f b

 

In fact, the surface wave detection and SERS or have their own wins, relative to the use of the environment and conditions are different. Where the larger difference is:

1. Raman technology is a molecular DNA that recognizes the molecular vibrational rotation, and there is no significant difference in Raman peak information for humidity.

2. Raman technology requires broad spectrum scanning, scanning time is second order of magnitude, there is no way to achieve real-time signal detection.

3. Raman technology is semi-quantitative technology, even if the enhanced sensitivity can not be fully realized quantitative detection.

4. In addition, this technology is expensive.

 

In other words, the advantage of graphene surface wave detection technology is the high sensitivity and ultra-fast response speed, the technology can replace the traditional SPR-based detection system, much higher than the SPR response speed and sensitivity for scientific research More accurate and fast data, can greatly improve the detection technology in science and technology, medical, security and other industries in the application effect.

 

Due to the presence of large amounts of free electrons on the surface of the metal, free electrons oscillate under the action of the incident light field. The oscillatory mode of the collective excited conductor electrons is called surface plasmon (SP). Under certain conditions, the incident light resonates with the oscillating electrons of the metal thin film, and the absorption of the incident light is significantly enhanced. This phenomenon is called "surface plasmon resonance (SPR)".

 

The SP oscillation frequency is determined by two factors:

1). The properties of metal nanoparticles (such as size), shape, and composition of different nanoparticles will cause the distance between the positive and negative charge of the surface difference, resulting in the change of the response force, and finally the red or blue shift of the spectrum;

2). The surrounding dielectric, the surrounding dielectric will mask the surface charge of the nanoparticles, causing the red shift of the spectrum, which is the application of nano-plasma in the basis of sensing.

 

SPR sensor is based on the surface plasmon resonance absorption based on the development of a device, the principle is mainly the plasma resonance frequency (or resonance angle) due to the metal film adjacent media changes in the refractive index changes, causing the Extinction spectrum movement. When the refractive index of the adsorbed molecules is different from the refractive index of the surrounding environment, the reaction of the biomolecules adsorbed on the surface of the substrate and the target molecules changes the refractive index of the surface of the substrate, causing the movement of the formant to achieve the detection of the target substance. The sensitivity of the SPR sensor is determined by the type of surface adsorbed molecules and the intensity of the electromagnetic field on the surface of the nanoparticles.

 

Surface-enhanced Raman scattering (SERS) is a non-destructive spectral detection method that provides detailed information about the molecular structure. The low energy electrons formed by the photoexcitation of the metal surface can enhance the localized electric field of the plasma surface, resulting in a significant increase in the SERS signal. For example, by optimizing the size, shape and aggregation state of silver and gold nanoparticles, a SERS enhancement factor of up to 1014 times of magnitude can be obtained. It is found that the size of the electric field is related to the material, size, shape, excitation wavelength and polarization of the nanostructures. Therefore, the resonant characteristics of the surface plasmas can be modulated by designing the shape and size of the nanostructured materials to improve the SERS Sensitivity of single molecule detection.

 

This is true, SERS phenomenon mainly from the surface plasmon resonance (SPR) caused by electromagnetic field (physical) enhancement, that is, strong SERS activity of the substrate must be suitable for SPR, with a certain degree of roughness of the "free electron gas" And found that the SERS activity of the substrate was directly related to the nature, scale and shape of the nanoparticles or nanostructures. This clearly reveals that SERS is not only a combination of surface science and Raman spectroscopy, but also an important part of nanoscience.

 

The low energy electrons formed by the photochromic surface of the metal surface not only lead to the enhancement of the local field photoelectric field on the surface of the metal nanostructures, but also induce the photophysical and chemical processes of the adsorbed molecules. Compared with SPR sensing technology, SERS process is more focused on the laser, molecular and metal nano-structure of the three complex interactions, it can provide more detailed and microscopic structural information. Take a chart of SERS to show that each tone can be regarded as a "fingerprint", you have to establish a "fingerprint database" for each tone, through the Raman spectrum can be compared to the wave type, and finally to Humidity frequency data into language information, with sound equipment sound. Therefore, it is necessary to clarify that the technology is not in the world in the leading level; Moreover, the most time is to establish a sound database, and each person's tone is different, for personal use, this product to come out there are many threshold you jump over.

 

v2 4c158f048bc926061651df48a82cdd79 b

more