Boronized Cold Spray Nozzle Prevents Powder Clogging
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Solution Overview
Problem
The cold spray process is hindered by nozzle clogging due to adhesion of powders, particularly when using high-pressure helium and high gas temperatures, leading to frequent nozzle repair and replacement, which limits the duration of industrial processes.
Innovation Solution
A cold spray nozzle with a boronized cemented carbide surface, where boron is diffused into the WC-Co substrate to form boride layers, reducing powder adhesion and enhancing surface hardness, thereby preventing clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-pressure helium and high gas temperatures are used to achieve high particle velocities and best properties, then particle velocity and coating properties are improved, but nozzle clogging increases significantly
Solution Approach 1:
The patent applies surface boronization treatment to the nozzle, changing the chemical composition and surface properties of the nozzle material. This creates a boron-enriched surface layer that reduces powder adhesion through modified surface chemistry, allowing high-velocity spraying without clogging
Solution Approach 2:
The patent creates a composite structure in the nozzle wall with a boron-enriched surface layer and a tungsten carbide-cobalt bulk material. This composite structure combines the adhesion-resistant properties of boronized surface with the mechanical strength of the carbide substrate
2Strength
If conventional cemented carbide nozzles are used, then nozzle robustness and durability are achieved, but powder adhesion causes frequent clogging and process disruption
Solution Approach 1:
The patent applies boronization treatment before the nozzle enters service, creating a protective surface layer in advance. This preliminary modification prevents powder adhesion from the start, eliminating clogging issues before they can occur during the spraying process
Solution Approach 2:
The patent converts the naturally occurring cobalt phase in WC-Co nozzle, which normally promotes powder adhesion, into a beneficial element by inducing boron diffusion that forms boride compounds. This transforms the harmful adhesion-promoting cobalt surface into a beneficial adhesion-resistant boronized surface
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 boronized nozzle significantly reduces clogging during cold spray deposition, allowing for extended continuous spraying and improved powder flow properties, enabling longer process durations and reduced material costs.
Implementation Method 1
boron is diffused into the WC-Co substrate to form boride layers
Data Source
Figure 1
Figure 1A
Figure 2
AI summary
A spray nozzle is provided having a body with a flow passage. At least along a portion of the flow passage the body has a depth-wise compositional variation having a cemented carbide first region and a cemented carbide second region closer to the flow passage than the first region, and having a higher boron content than a boron content, if any, of the first region. Also provided is a method of manufacturing such a spray nozzle whereby a boriding powder is placed into a passageway of a cemented carbide precursor of the spray nozzle and the precursor is heated so as to cause boron from the bonding powder to diffuse into the precursor.