12dz Chapter 1257
Chapter 1257
They simply cannot withstand seawater temperatures exceeding 100 degrees Celsius.
However, after Lin Wei and her group arrived at the mid-air fortress, they discovered a new type of alloy with a high boiling point.
Lin Wei intuitively believed that as long as she could find a way to incorporate boiling point alloy material into the original first-generation high-temperature coating, she would definitely be able to develop a high-temperature resistant coating that could withstand seawater at 100 degrees Celsius.
However, there is a difficulty that cannot be overcome.
Although boiling point alloys have high melting points, they are completely incompatible with existing nano-ceramic high-temperature coatings. If they are forcibly combined, the coating will crack at high temperatures.
Lin Wei and her team's initial idea was to melt the boiling point alloy into a liquid state and spray it onto the surface of the ceramic coating.
However, as soon as the alloy steel in the furnace came into contact with the coating, it made a piercing "sizzle" sound, and the coating was instantly burned by the high temperature, causing it to bubble and peel off.
Later, they changed their approach and tried using powder metallurgy to grind the boiling point alloy into fine powder, mix it into the raw materials of the ceramic coating, and sinter them together.
The result was even worse!
As soon as the temperature in the sintering furnace reached 1,500 degrees Celsius, the alloy powder began to clump together, making it impossible to disperse evenly in the coating. The final product was pitted and uneven, and would crumble into dust if poked with a probe.
"The problem lies in the coefficients of thermal expansion of the two materials!" Lin Wei looked at her team members. "The coefficient of thermal expansion of the boiling point alloy is three times that of the ceramic coating! When the temperature changes, one expands faster than the other, it's no wonder it cracks! How do we solve this!"
Xiaoxue, who was standing next to her, was also very anxious.
These days, she has been thinking day and night about how to make these two materials compatible.
She looked up and tentatively said, "Sister Lin, how about we try adding a transition layer in the middle? Using a material with a thermal expansion coefficient between the two?"
Lin Wei suddenly raised her head, a glint of light flashing in her eyes.
Yes, a transition layer!
How could they forget such a crucial step!
Soon, the roar of machines filled the laboratory of the research institute once again.
They searched through the base's materials warehouse and finally found a nickel-based high-temperature alloy sheet whose coefficient of thermal expansion was just between that of boiling point alloys and ceramic coatings.
This time, they changed the process.
First, a two-millimeter-thick ceramic-based high-temperature coating is sprayed onto the surface of the ship's steel plate, and then it is sent into a sintering furnace and sintered at a high temperature of 1200 degrees Celsius.
Next, the nickel-based alloy sheet is firmly bonded to the ceramic coating with high-temperature adhesive, and then the edges of the sheet are welded to the steel plate using laser welding to prevent seawater from seeping in.
Finally, the boiling point alloy, ground into micron-sized powder, is uniformly coated onto a nickel-based sheet using plasma spraying to form an alloy layer one millimeter thick.
The entire process needs to be error-free.
When spraying ceramic coatings, if the temperature is even slightly higher, the coating will carbonize.
If it's even a fraction too low, it won't bond firmly with the steel plate.
Even in the final plasma spraying process, the movement speed of the spray gun must be precise to the millimeter per second. If it's too slow, the alloy powder will pile up into clumps; if it's too fast, a dense protective layer cannot be formed.
After seven days and seven nights of hard work, a three-square-meter composite coating sample finally lay quietly on the lab table.
Lin Wei and her team haven't slept for several days.
Success or failure depends on this!
They all seemed tireless, huddled together.
Lin Wei placed the sample into a test chamber that simulated a seawater environment.
The seawater in the test chamber was prepared according to the current sea surface water quality, with a temperature as high as 100 degrees Celsius, and high concentrations of sulfides and acidic substances were added.
Everyone held their breath, staring at the test chamber's display screen.
One hour, two hours, one day, two days...
The coating thickness reading on the display screen decreased slowly, but there was no sign of cracking or peeling.
Forty-eight hours later, the value suddenly plummeted.
At the junction of the nickel-based alloy sheet and the ceramic coating, a gap almost invisible to the naked eye appeared. High-temperature seawater seeped into the gap and instantly swelled and peeled off the ceramic coating.
Once the nickel-based sheet lost its protection, it quickly became riddled with holes due to corrosion.
Finally, the boiling point alloy layer on the surface peeled off along with it.
"It's done!" Xiaoxue was the first to react, screaming as she rushed over and hugged Lin Wei. "Sister Lin, we did it! We can last two days!"
Lin Wei's paralyzed hands were covered with blisters from the high temperature burns, and her lips were dry and cracked from not drinking enough water for several days.
But at this moment, a smile of relief appeared on her face.
However, after the joy came the heavy reality.
This coating can only be used once.
The bonding strength between the nickel-based sheet and the ceramic coating can only withstand two days of immersion in high-temperature seawater.
Moreover, although the boiling point alloy layer coated by plasma spraying is dense, it cannot withstand the high pressure of the seabed.
Sailing on the sea, where the water pressure is low, it can last for another two days.
If you dive to the seabed, the water pressure will deform the nickel-based sheet, and the coating will crack even faster. It can only last for half a day at most.
Even so, this is already a glimmer of light in a desperate situation.
The research institute is busy developing a second-generation high-temperature coating.
Meanwhile, the base devoted all its resources to the reconstruction of the fortress.
The tsunami and earthquake that lasted three days and three nights had shaken the foundation of the semi-aerial fortress.
The fortress was built on the main island and No. 1 secondary island, and was originally supported by boiling point alloy piles that penetrated deep into the rock strata.
However, the landslides triggered by the earthquake left many pile foundations exposed, and some even developed cracks.
The walls of the fortress were covered in spiderweb-like cracks in many places.
At its widest point, a fist can fit inside.
However, due to the inherent strength of the boiling point alloy, their population of 10,000 was able to barely survive on the mid-air fortress.
But if something goes wrong, they could perish in the boiling sea along with the collapsing fortress.
Although the two giant machines are still there, the current high temperatures have rendered them completely useless.
Those massive steel machines, once started, their engine temperatures soar to over 100 degrees Celsius, making it difficult to even start them up, let alone work.
Left with no other choice, everyone had to put on air-conditioned suits and repair the damage bit by bit by hand.
Fortunately, the engineering team that built this fortress was farsighted.
They took all sorts of factors into account when designing the foundation.
One of the most important design features is the addition of a buffer layer consisting of high-strength springs and dampers between the pile foundation and the main body of the fortress.
This buffer layer can normally offset the impact of sea winds and waves on the fortress, and when an earthquake occurs, it can act like a spring to absorb the energy of seismic waves, preventing the pile foundation and the main structure from directly colliding.