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(FYP) Koh JF, R
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1st prototype
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Started from here
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Limitations
During this project, it was observed that there are limitations when working with liquid metal, EGaIn. This section aims to highlight and elaborate on these limitations when employing EGaIn as an SMH. Some of these limitations will question the practicality of using to employ this SMH.
1 Limited materials
Gallium is highly corrosive towards many common metals at room temperature. In some cases, the corrosive reaction is increased during the wetting process. Some metals suffer from embrittlement and corrosion as the Gallium will start to attack the metal. This limits the choices of metal that can be used in the creation of this SMH.
Material selection is limited further when the activating agent for Liquid gallium is an alkali, Sodium Hydroxide (NaOH). NaOH is known to be a corrosive solution that degrades metals. It is found that pure copper is a suitable material that can be wetted by Gallium without corroding. Hence research into how copper reacts when submerged in NaOH was made. It is found that, the corrosion rate of copper is not instantaneous, and it takes time for the metal to fully corrode. In the previous project, it is proven that after wetting, CuGa Pads take a longer period to corrode when kept in NaOH.
2 Limited prolonged usage
Even though it takes time for the Pad to corrode, it leads to the limitation of prolonged storage. Once the SMH is prepped, it is advised to be used as soon as possible. This is because the corrosion can reach a point where majority of the Pad is corroded and the CuGa area of the Pad becomes too small to successfully program the SMH.
3 Limited repeated usage
After repeated activations, it is observed that the CuGa pads corrodes faster. This reduces the number of repeated uses of the SMH after being activated. The corrosion rate escalates such, within an hour with 7 activations, the SMH could no longer be used as majority of the Pad surface had corroded.
4 Cost effectiveness
It is not financially effective to employ EGaIn in huge amounts due to its cost. For context, the price of EGaIn is comparative to prices of platinum and palladium. EGaIn costs about USD38 to USD41 per gram and Platinum costs around USD29 per gram and Palladium about USD34 per gram.
5 Health Hazard
Both EGaIn and NaOH are both hazardous to work with as both are corrosive. They require careful storage and storage options become limited as both do not work well with a lot of materials. If not stored carefully or used with the improper materials, like metals, it may cause structural and health hazards as both will degrade materials overtime.
6 Working Environment
Most tests were conducted in a Fumigation hood with constant air flow and regulated temperature. However, on one of the tests, the hood was turned off. Due to the lack of air flow, the working environment temperature had risen and became more humid. It was observed that under these conditions, there was no deformation reaction of the EGaIn droplet in NaOH. It was suspected that the power supply could have been out of power, however, after changing the batteries, there was still no reaction observed. Upon fixing the Fumigation hood, the EGaIn droplet reacted normally. This proved that the environment does affect the performance of EGaIn in NaOH, hence there is a limitation to the working environment. More investigations must be carried out to find the conditions that caused this occurrence.
1 Limited materials
Gallium is highly corrosive towards many common metals at room temperature. In some cases, the corrosive reaction is increased during the wetting process. Some metals suffer from embrittlement and corrosion as the Gallium will start to attack the metal. This limits the choices of metal that can be used in the creation of this SMH.
Material selection is limited further when the activating agent for Liquid gallium is an alkali, Sodium Hydroxide (NaOH). NaOH is known to be a corrosive solution that degrades metals. It is found that pure copper is a suitable material that can be wetted by Gallium without corroding. Hence research into how copper reacts when submerged in NaOH was made. It is found that, the corrosion rate of copper is not instantaneous, and it takes time for the metal to fully corrode. In the previous project, it is proven that after wetting, CuGa Pads take a longer period to corrode when kept in NaOH.
2 Limited prolonged usage
Even though it takes time for the Pad to corrode, it leads to the limitation of prolonged storage. Once the SMH is prepped, it is advised to be used as soon as possible. This is because the corrosion can reach a point where majority of the Pad is corroded and the CuGa area of the Pad becomes too small to successfully program the SMH.
3 Limited repeated usage
After repeated activations, it is observed that the CuGa pads corrodes faster. This reduces the number of repeated uses of the SMH after being activated. The corrosion rate escalates such, within an hour with 7 activations, the SMH could no longer be used as majority of the Pad surface had corroded.
4 Cost effectiveness
It is not financially effective to employ EGaIn in huge amounts due to its cost. For context, the price of EGaIn is comparative to prices of platinum and palladium. EGaIn costs about USD38 to USD41 per gram and Platinum costs around USD29 per gram and Palladium about USD34 per gram.
5 Health Hazard
Both EGaIn and NaOH are both hazardous to work with as both are corrosive. They require careful storage and storage options become limited as both do not work well with a lot of materials. If not stored carefully or used with the improper materials, like metals, it may cause structural and health hazards as both will degrade materials overtime.
6 Working Environment
Most tests were conducted in a Fumigation hood with constant air flow and regulated temperature. However, on one of the tests, the hood was turned off. Due to the lack of air flow, the working environment temperature had risen and became more humid. It was observed that under these conditions, there was no deformation reaction of the EGaIn droplet in NaOH. It was suspected that the power supply could have been out of power, however, after changing the batteries, there was still no reaction observed. Upon fixing the Fumigation hood, the EGaIn droplet reacted normally. This proved that the environment does affect the performance of EGaIn in NaOH, hence there is a limitation to the working environment. More investigations must be carried out to find the conditions that caused this occurrence.
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(FYP) Tey YL
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电池制造全过程，超超超详细！
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The strength of the electric field required to polarize a ferroelectric material and generate noticeable repulsion between like poles or attraction between opposite poles depends on the type of ferroelectric material, its coercive field, and its polarization characteristics.
Generally, the coercive field is a key parameter for ferroelectric materials, representing the minimum electric field strength needed to reverse the polarization. Below are the coercive field ranges for some common ferroelectric materials:
It's important to note that applying an excessively high electric field may cause dielectric breakdown or damage the material, so the field strength should be within the material's tolerance limits. |
铁电粉末在电场作用下是否分散取决于颗粒间的吸引力（偶极吸引、表面静电力）与电场诱导的分散力之间的平衡：
- 弱电场：颗粒可能保持吸引，难以分散。
- 强电场：颗粒间吸引力可能被克服，导致分散。
- 粉末粒径和介质环境也会显著影响分散效果。
