Major Heavy Industry: Starting with a Fake Marriage

Chief Engineer Chen walked over, looked at the deformed sample, and then at the readings on the tensile testing machine. Her face was expressionless, but her breathing was heavier, and her chest heaved more than usual. She reached out and touched the deformed sample, her fingertips gliding across the coating surface.

"No need. It's acceptable."

A moment of silence fell over the lab. Then Sun Deming let out a soft "Yeah!", a quiet sound that rang out clearly in the quiet lab, like a pebble thrown into still water. Huang Deqing stood up from the corner, stretched his back, and his bones cracked a few times. He lit a cigarette, took a drag, and slowly exhaled. The smoke dispersed under the light, turning into a pale blue cloud before being sucked away by the ventilation duct.

Jiang Cheng leaned back in his chair and let out a long sigh. His back was covered in sweat, and his shirt clung to his skin, feeling cool as if someone had placed a block of ice on his back.

"This is just a mock-up." Chief Engineer Chen's voice pulled him back to reality, like someone tapping a bell in his ear. "It's not a real blade yet. Just because the mock-up is up to standard doesn't mean the real blade is up to standard. The real blade has a more complex air-film pore layout, forty-eight pores distributed in different locations, with different diameters and angles. It has more complex curved surfaces; the underside of the blade is convex, and the leaf basin is concave. The coating is easier to spray thin on the convex surface and thicker on the concave surface. It also has a thinner wall thickness; the thinnest part of the blade is only 1.5 millimeters. If the heat input is slightly too high, the blade will deform. All of these factors will affect the uniformity and bonding strength of the coating. Next step, install the real blade."

Jiang Cheng nodded.

The real blades were delivered from Chief Engineer Zhao's office, packaged in specially made foam boxes, one blade per box, five in total. The foam boxes were white, with the shape of the blades cut out inside to hold them securely. The blades were silvery-white, shaped like twisted willow leaves, with fine, dense pores arranged in neat rows, like a honeycomb. The blade walls were very thin, making them feel light and airy in the hand, like real leaves, as if a gust of wind would carry them away. Jiang Cheng picked up a blade and examined it against the light. There was a faint mark in the middle of the blade, not a crack, but a casting flow line, like the lines on a palm. He placed the blade under a microscope and carefully observed each pore. The position, diameter, and smoothness of the pore walls all met the requirements of the drawings. He checked each of the forty-eight pores to ensure they were not blocked by casting wax.

"How much is this leaf worth?" Sun Deming asked from the side, his voice filled with a hint of awe, as if he were asking about the price of an antique.

The technician sent by Chief Engineer Zhao said, "One piece costs about two thousand yuan. Imported ones are even more expensive, costing five thousand. This is a high-temperature alloy, and the casting process is very complex, resulting in a low yield. From casting to processing, one piece requires dozens of steps and takes two months."

Sun Deming gasped. "Two thousand yuan? If we ruin one coat of paint, two thousand yuan is gone?"

Jiang Cheng ignored him. He fixed the blade to the workbench and clamped its root with a special fixture. The fixture was made of aluminum alloy and was machined very precisely, fitting perfectly into the blade's tenon without damaging the surface. He began adjusting the spraying parameters. The parameters of the simulated part could serve as a starting point, but they couldn't be copied verbatim. The walls of the real blade were thinner, so the heat input needed to be controlled more strictly, otherwise it would cause the blade to deform. The layout of the film cooling vents was more complex, and to ensure the coating wouldn't clog the vents, the spraying angle and trajectory needed to be adjusted.

He spent an hour designing a new spraying path. The spray gun sprayed the blades from five different angles, each corresponding to a set of parameters. He input the path into the control program, checked it three times to make sure there were no errors, and then checked it again.

"Let's begin."

The spray gun ignited, and flames shot out. This time, he was even more nervous than before. His palms were sweaty, and his fingers slipped as he pressed the buttons on the control panel, taking two tries to press them. The simulation could be restarted if it failed, but there were only five real blades, each worth two thousand yuan. One failure meant a loss of two thousand yuan. More importantly, the number of blades was limited; once they failed, they were gone. Requesting new blades would take another two months.

He controlled the robotic arm, guiding the spray gun along the pre-set path. The first layer was very thin, almost transparent, invisible against the silvery-white substrate; only when held up to the light could a faint mist be seen. The second layer darkened, turning grayish-white, like a layer of dust on a leaf. The third, fourth, and fifth layers followed. After each layer, he inspected the air film pores with a magnifying glass to ensure they weren't blocked. Forty-eight pores, requiring inspection after every layer—a huge workload, but he dared not skip any.

The spraying was finished. He turned off the equipment and waited for the blades to cool. The cooling process was slow; he stood at the worktable, watching the blades gradually cool down from their high temperature. The coating surface undergoes slight shrinkage during cooling, and uneven shrinkage can cause microcracks. He carefully inspected every part with a magnifying glass—the underside of the blade, the base, the edge, and the root—and found no cracks. The blades were not deformed, and the readings on the fixture remained unchanged.

"Inspect the air film pores," Chief Engineer Chen said.

Jiang Cheng picked up a fine needle and began to poke at the air pores one by one. There were forty-eight air pores in total on the leaf, distributed in different parts of the leaf. Some were on the underside of the leaf, some on the leaf base, some on the leading edge, and some on the trailing edge. He poked at them one by one, marking each one with a checkmark in his notebook. All forty-eight pores were cleared. When he finished poking the last pore, his fingers were trembling, and the tip of his pen drew a long line on the paper.

"Surface inspection," Chief Engineer Chen said.

He placed the leaf under a microscope to examine the microscopic morphology of the coating surface. At 100x magnification, no cracks were found. At 200x magnification, no bubbles were found. At 500x magnification, no peeling was observed. The coating grains were fine and tightly packed, resembling a layer of uniform sand. The coating thickness was measured using an eddy current thickness gauge. The designed thickness was 300 micrometers, and the actual average value was 295 micrometers, within the tolerance range. The readings at the five measurement points were 296, 294, 297, 293, and 295 micrometers, showing excellent uniformity.

"We can't do destructive testing on the bonding strength, since the blades will still be used. We can only do ultrasonic testing," said Chief Engineer Chen.

Ultrasonic testing involves scanning the coating surface with a probe and judging the bonding strength between the coating and the substrate by the intensity of the reflected waves. The probe is a small cube coated with a sticky coupling agent, like glue. Jiang Cheng held the probe and scanned it bit by bit across the blade surface. A waveform was displayed on the instrument's screen, with the height of the peak representing the bonding strength. He stared at the waveform, his heart pounding, as if awaiting a verdict.