Amorphous Inner Pipe Coating for Small-Diameter Corrosion Resistance
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Solution Overview
Problem
Existing methods for coating pipes with organic and inorganic materials to enhance corrosion and wear resistance are difficult to apply to pipes with small inner diameters, particularly those less than 7.62 cm or with an inner diameter to length ratio of 1:2, due to limitations in thermal spraying equipment and coating techniques.
Innovation Solution
A method involving the use of an Fe-based amorphous alloy powder, prepared by gas atomization, is applied to the inner surface of pipes through thermal spraying, maintaining the amorphous structure even after coating, thereby improving coating density, corrosion resistance, and wear resistance. The process involves coating the alloy powder on a plate, bending it into a pipe shape, and seaming the ends to form a seamless pipe with an amorphous inner surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal spraying equipment is used to coat pipe inner surfaces, then corrosion resistance and wear resistance are improved, but the method becomes inapplicable to pipes with small inner diameters (less than 7.62 cm)
Solution Approach 1:
Instead of coating the pipe inner surface directly through thermal spraying, the patent inverts the process by coating the outer surface of a mandrel with amorphous alloy powder, then forming the pipe around this coated mandrel. This allows the amorphous coating to become the inner surface of the finished pipe, enabling coating of small diameter pipes that would be inaccessible to conventional thermal spraying equipment.
Solution Approach 2:
The patent introduces a mandrel as an intermediary object to facilitate the coating process. The mandrel serves as a temporary support structure that carries the amorphous alloy coating, which is then transferred to form the inner surface of the pipe. This intermediary approach enables coating of pipes with inner diameters too small for direct thermal spraying access.
2Manufacturing precision
If conventional thermal spraying is used to coat pipe inner surfaces, then coating density is improved, but the amorphous structure is lost during the coating process
Solution Approach 1:
The patent changes the thermal processing parameters by using a lower temperature forming process (such as incremental rolling or pressurized forming) after the amorphous coating is applied to the mandrel. This controlled parameter change allows the coating to be densified and transferred to the pipe inner surface while maintaining the amorphous structure, avoiding the high temperatures that would cause crystallization.
Solution Approach 2:
The amorphous alloy coating is applied to the mandrel surface in advance before the pipe forming process. This preliminary coating ensures that the amorphous structure is established prior to any thermal or mechanical processing, allowing subsequent forming operations to proceed without compromising the amorphous phase integrity.
3Reliability
If amorphous alloy powder is coated on pipe inner surfaces, then coating density and corrosion resistance are improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the coating application and pipe forming operations into a single integrated process. By coating the mandrel with amorphous alloy powder and then forming the pipe around this coated mandrel, the process combines what would otherwise be separate coating and forming steps, reducing overall manufacturing complexity while achieving high-quality amorphous inner surfaces.
Solution Approach 2:
The coated mandrel serves a dual function: it acts as both the coating substrate and the forming tool. The amorphous alloy coating on the mandrel automatically transfers to the pipe inner surface during the forming process, eliminating the need for separate coating application equipment for the pipe itself and simplifying the manufacturing system.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method allows for efficient coating of pipes with small inner diameters, maintaining a high amorphous phase proportion, resulting in improved coating density, corrosion resistance, and wear resistance, with enhanced productivity and ease of manufacturing.
Implementation Method 1
a method involving the use of an Fe-based amorphous alloy powder, prepared by gas atomization, is applied to the inner surface of pipes through thermal spraying
Implementation Method 2
maintaining the amorphous structure even after coating, thereby improving coating density, corrosion resistance, and wear resistance
Data Source
Figure 1(a)~1(e)
Figure 2(a)~2(c)
Figure 3(a)~3(d)
AI summary
Disclosed is a coated pipe having an amorphous inner surface and a method of manufacturing the same, whereby an amorphous alloy powder is coated on an inner surface of the pipe, thus ensuring that an amorphous structure is maintained after coating and thus coating density, corrosion resistance, and wear resistance of the pipe are improved. The coated pipe having an amorphous inner surface includes: a pipe; and a coating layer provided on an inner surface of the pipe, wherein the coating layer is an alloy or metal layer of a material different from a material of the pipe and contains an amorphous phase in a proportion of equal to or greater than 90%.