Multilayer Hard Coating for Molds With Reduced Droplet Formation
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Solution Overview
Problem
Mold coatings face challenges in durability due to droplet formation in arc ion plating methods, leading to degradation of adhesive force and potential cracking, especially when working with high-strength materials in hot stamp methods where press molding and quenching occur simultaneously.
Innovation Solution
A coated mold with a hard coating configuration that includes alternately laminated layers of Cr-based nitride and (V1-aMa) nitride or carbonitride, where M is Mo or W, with specific atomic ratios and thicknesses, applied using a PVD method to reduce droplet formation and enhance durability and sliding properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If arc ion plating method is used to form hard coating on mold, then coating hardness and abrasion resistance are improved, but droplet formation occurs leading to degradation of adhesive force and coating durability
Solution Approach 1:
The coating is divided into multiple thin layers (5-10 nm each) with alternating composition (Cr-rich layers and V-rich layers) deposited in sequence. This segmented multilayer structure prevents droplet formation by limiting the thickness of each deposition cycle and creating a fine-lamellar architecture that enhances adhesion while maintaining hardness.
Solution Approach 2:
The coating process uses dynamic control of deposition parameters including alternating the type of target material (Cr vs V) between cycles, adjusting deposition thickness to 5-10 nm per cycle, and controlling the number of repetition cycles. This dynamic adjustment optimizes the balance between hardness and adhesion, preventing droplet formation while maintaining coating durability.
2Reliability
If PVD method is used to reduce droplet formation, then coating adhesion and durability are improved, but coating temperature is lower resulting in reduced softening control of mold
Solution Approach 1:
The invention changes the deposition parameters by controlling each cycle to deposit only 5-10 nm thickness and repeating the cycle multiple times. This parameter control allows PVD method to achieve adequate hardness while maintaining lower temperatures that prevent excessive mold softening, thus improving adhesion and durability without compromising temperature control.
3Ease of operation
If multilayer structure with Cr-based nitride and V-based nitride is formed, then sliding properties and galling resistance are improved, but manufacturing complexity increases
Solution Approach 1:
The coating is segmented into alternating Cr-rich and V-rich layers, each 5-10 nm thick, deposited through repeated cycles. This segmentation creates a fine-lamellar multilayer structure that provides excellent sliding properties and galling resistance while using a systematic deposition process that manages manufacturing complexity through standardized cycle repetition.
Solution Approach 2:
The invention controls the composition ratio of Cr and V in each layer through parameter adjustment during deposition, with Cr-rich layers providing hardness and V-rich layers providing sliding properties. By controlling the number of repetition cycles and deposition thickness, the manufacturing process manages complexity while achieving the desired multilayer structure with optimized 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 solution effectively reduces droplet formation, improves durability, and maintains excellent sliding properties by stabilizing the coating structure and increasing Young's modulus and hardness, thereby enhancing the mold's resistance to abrasion and galling.
Implementation Method 1
applied using a PVD method to reduce droplet formation and enhance durability and sliding properties
Data Source
AI summary
A coated mold which can exhibit good sliding properties, and has further reduced droplets and excellent durability. The coated mold has a hard coating on a work surface, the hard coating including layer A in which layer a1 and layer a2 are alternately laminated, wherein the layer a1 is composed of a Cr-based nitride and has a thickness of 100 nm or less, and the layer a2 is composed of a nitride or carbonitride of (V1-aMa) (M is at least one selected from Mo and W), has an atomic ratio a of M to the sum of V and M of 0.05 or more and 0.45 or less, and has a thickness of 80 nm or less. Also: a method for manufacturing a coated mold; and a hard coat-forming target which can be used in the method for manufacturing a coated mold.