Cold Spray Coating with Adiabatic Phase Transformation
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Solution Overview
Problem
Existing coating techniques, such as cold spraying, do not effectively facilitate phase transformations or reactions during the deposition of powders on solid substrates, limiting the creation of coatings with varied properties suitable for diverse applications.
Innovation Solution
The method involves using cold spraying with inorganic powders and high-energy milling to create mixtures of phase transformation or reaction precursor reagents, which undergo adiabatic reactions upon impact, potentially combined with thermal treatment to produce coatings with enhanced properties like high resistance and self-lubrication, utilizing a convergent-divergent Laval nozzle to achieve impact speeds greater than 350 m/s.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cold spraying is used to deposit powder on a solid substrate, then coating can be formed, but phase transformations or reactions during formation or application of the coating are excluded
Solution Approach 1:
The invention changes the temperature parameter during the spraying process by heating the carrier gas to temperatures approaching or exceeding the melting point of the powder particles, enabling phase transformations and chemical reactions that were previously excluded in conventional cold spraying
Solution Approach 2:
The invention utilizes phase transitions by heating the carrier gas and powder particles to temperatures that induce melting and subsequent solidification, allowing formation of coatings with transformed phases and improved properties
2Stability of the object's composition
If the carrier gas is heated to a temperature lower than the melting temperature of the powder particles, then the particles maintain their mechanical properties, but phase transformations cannot occur
Solution Approach 1:
The invention changes the temperature parameter by heating the carrier gas to temperatures at or above the melting point of the powder particles, enabling phase transformations while controlling the duration and intensity to manage the trade-off between mechanical property stability and phase variety
3Productivity
If high impact speed is used to deposit powder, then coating deposition is achieved, but controlled phase transformations are difficult to实现
Solution Approach 1:
The invention applies preliminary action by heating the carrier gas and powder particles to the required temperature before impact occurs, ensuring that phase transformations are initiated under controlled thermal conditions rather than relying solely on adiabatic heating from impact
Solution Approach 2:
The invention changes multiple parameters simultaneously - temperature of the carrier gas, particle size distribution, and impact velocity - to create optimal conditions for controlled phase transformations while maintaining high deposition rates
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
This approach results in coatings with at least 30% volume of phases different from the initial powders, offering high wear and corrosion resistance or self-lubricating properties, suitable for various industrial applications, with the ability to tailor properties through choice of starting materials and processing conditions.
Implementation Method 1
a jet consisting of the powder mixture to be deposited and a carrier gas... expelled from a convergent-divergent nozzle (Laval nozzle)... impact of the jet on the substrate occurs at a speed of more than 350 m/s
Implementation Method 2
Before mixing the carrier gas is heated to a temperature lower than the melting temperature of the material of the powder particles... sufficiently high to reduce their mechanical properties so that the particles undergo plastic deformation during deposition
Implementation Method 3
the concepts of 'reaction' and 'phase transformation' have the same meaning... adiabatic temperature is mentioned. It is calculated by the ratio of the reaction (or phase transformation) heat and the specific heat of the reaction (or phase transformation) products
Implementation Method 4
citing exothermic reactions taking place in the formation of FeAl intermetallic phase
Data Source
AI summary
A method for forming a surface coating on at least a part of a solid substrate, comprising a step of cold spraying a flow comprising at least one carrier gas, and particles suitable for deposition on the said substrate, said flow having a speed of more than 350 m/s; The particles are obtained from inorganic materials and have dimensions smaller than 200 μm. One or more mixtures of reaction precursor reagents are present in at least some of the particles. The mixtures are obtained from at least one pair of phases. The mixtures of reaction precursor reagents are characterized by at least one reaction having an adiabatic temperature of at least 800 °C.