Plasma-Sprayed TiN Coating for Mold Wear Resistance
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Solution Overview
Problem
Current TiN coating layers prepared by CVD, PVD, and thermal spraying technologies are either thin with reduced mechanical properties or thick with high porosity and brittleness, making it difficult to control their quality and achieve optimal hardness and toughness.
Innovation Solution
A TiN coating layer is prepared using a plasma spraying method with agglomerated TiN powder (72% Ti, 28% N) that forms spherical aggregates of 40-80 μm, sprayed with specific parameters (argon, hydrogen, and power settings) to create a dense layer with TiN, TiO, and Ti3O phases, reducing porosity and improving bonding with the matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If CVD or PVD methods are used to prepare TiN coating layers, then the coating layers have low porosity and good quality control, but the coating layers are relatively thin resulting in reduced mechanical properties
Solution Approach 1:
The patent combines CVD/PVD deposition processes with thermal spraying technology to create a composite coating structure. The coating is prepared in two stages: first forming a dense base layer through CVD/PVD, then building up thickness with thermal sprayed TiN material, achieving both quality control and mechanical strength
Solution Approach 2:
The patent creates a composite coating structure with different material phases including TiN, TiO2, and intermediate phases. This composite structure leverages the low porosity of CVD/PVD layers and the thickness advantage of thermal spraying, achieving improved mechanical properties while maintaining coating quality
2Volume of moving object
If thermal spraying reaction technology is used to prepare thicker TiN coating layers, then the coating layer thickness is increased, but more pores exist in the coating layers and the coating layers have large brittleness
Solution Approach 1:
The patent performs preliminary surface treatment and substrate preparation including roughening, cleaning, and pre-coating with a transition layer before thermal spraying. This preliminary action creates a better foundation that reduces porosity and improves bonding, allowing thicker coatings with better quality control
Solution Approach 2:
The patent optimizes thermal spraying parameters including plasma power, spraying distance, substrate temperature, and TiN powder characteristics. By carefully controlling these parameters, the process achieves thicker coatings with reduced porosity and improved density while maintaining quality
3Productivity
If plasma spraying is used to directly spray TiN powder, then a relatively thick coating layer can be prepared within a short time and the toughness is improved, but oxidation occurs during the spraying process to form oxide phase of Ti
Solution Approach 1:
The patent converts the harmful oxidation effect into a beneficial feature by controlling the formation of TiO2 and other oxide phases. These oxides create a gradient structure that improves coating toughness and stress distribution, transforming the previously harmful oxidation into a desired property enhancement
Solution Approach 2:
The patent controls plasma spraying parameters including gas composition, plasma power, and substrate temperature to manage oxidation. By optimizing these parameters, the process achieves high deposition efficiency while controlling oxide content to beneficial levels that enhance coating performance
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 resulting TiN coating layer exhibits high hardness (1210HV0.1), improved fracture toughness (3.94MPa√m), and enhanced wear resistance, overcoming brittleness and porosity issues while simplifying the process and reducing costs.
Implementation Method 1
By directly spraying TiN powder with a plasma spraying technique
Implementation Method 2
melted particles chemically react with the surrounding medium during the melting and flight process
Implementation Method 3
oxidation of TiN occurs during the spraying process to form an oxide phase of Ti
Data Source
AI summary
Disclosed is an agglomerated TiN powder, the powder comprising spherical aggregates having particle diameters of 40 to 80 μm and formed by the agglomeration of Ti and N having the atomic fractions of 72% and 28% respectively. Also provided is a TiN coating obtained using the powder. The three-strong-peak phase of the coating is a TiN phase, and also has partial TiO, TiO2, and Ti3O oxide phases; the coating has layered distribution of bright and dark phases, and the joint between the interior of the layered structure and the layer structure is provided with a small number of pores; the joint between the coating and a base has no microscopic defects such as cracks and is well jointed. The supersonic plasma-sprayed TiN coating achieves hardness as high as 1210HV0.1, thereby enhancing the wear resistance of the coating. The coating has good fracture toughness, thereby enhancing the fracture mechanical performance inside of the coating and extending the fatigue life of the coating. Also provided are a preparation method for the TiN coating, and a mold coated with said TiN coating.