Cermet Powder Sintering in Carburizing Atmosphere
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing cermet and cemented carbide powders for 3D printing face challenges in achieving a microstructure with appropriate porosity and flowability, as conventional powders are too fragile and prone to sintering, leading to poor quality 3D printed parts with increased porosity.
Innovation Solution
A method involving forming a slurry with hard constituents, binder metal, and organic binder, followed by unsintered granule formation, sintering in a carburizing atmosphere between 1200°C and the solidus temperature, and a deagglomeration step to maintain spherical shape and prevent granule adhesion, resulting in a ready-to-print powder with controlled porosity and flowability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the granules are sintered to different degrees to prevent adhesion, then the granules can be separated, but the final sintered cermet or cemented carbide retains excessive porosity
Solution Approach 1:
A barrier powder (such as alumina, silica, or magnesia) is introduced as an intermediary substance between the cermet granules during storage and handling. This barrier powder prevents direct contact between granule surfaces, eliminating adhesion without requiring excessive sintering that would create porosity. The barrier powder is subsequently removed before final sintering, leaving clean granule surfaces ready for consolidation.
Solution Approach 2:
The granules are pre-sintered to a controlled degree before storage to develop sufficient surface strength to prevent deformation, but not so much that they adhere to each other. This preliminary sintering creates a stable intermediate state where granules can be handled and stored without adhesion problems, and then final sintering consolidates them with minimal porosity.
2Object-generated harmful factors
If a lower sintering temperature is used to prevent granule adhesion, then less metal binder melts together, but the granules become less dense with more pores
Solution Approach 1:
Barrier powder is applied to granule surfaces before storage and removed before final sintering. This allows the granules to be sintered at lower temperatures without adhesion, because the barrier prevents direct metal-to-metal contact that would cause sticking, while still achieving adequate density through the lower temperature sintering process.
Solution Approach 2:
The sintering temperature parameter is optimized to a specific range that balances two competing requirements: high enough to achieve adequate granule density and binders consolidation, but low enough to prevent excessive binder melting that would cause adhesion. The barrier powder enables this lower temperature regime to work effectively.
3Object-generated harmful factors
If barrier powder is added to prevent granule contact, then adhesion is prevented, but additional cleaning steps are required after sintering
Solution Approach 1:
The barrier powder is used as a disposable, temporary measure during storage and handling. It serves its protective function during the critical storage period, then is easily removed before final sintering. The simplicity and low cost of this temporary barrier make the additional cleaning step worthwhile, as it enables lower sintering temperatures and better quality control.
Solution Approach 2:
The barrier powder is applied in advance during granule preparation and storage to prevent adhesion problems from developing. By addressing the adhesion prevention issue preliminarily during storage rather than trying to solve it during final processing, the overall process complexity is reduced and quality is improved.
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 produces sintered granules with reduced porosity and maintained spherical shape, enhancing the flowability and quality of the cermet or cemented carbide powder for additive manufacturing, allowing for effective 3D printing with fewer processing steps.
Implementation Method 1
from the slurry forming unsintered granules
Implementation Method 2
sintering the granules at a temperature between 1200 and Ts° C.
Implementation Method 3
sintering the granules at a temperature between 1200 and Ts° C., where Ts is the highest temperature where the binder is still in a solid state for a specific cermet or cemented carbide composition, in a carburizing atmosphere
Data Source
AI summary
A method of making a ready-to-print cermet or cemented carbide powder of sintered granules includes the step of sintering the granules in a carburizing atmosphere. Due to the carburizing atmosphere, the granules will have less binder phase on the surface and will not sinter together and will be easy to deagglomerate and the granules will maintain its spherical shape. A powder made according to the method, as well as the use of the powder in an additive manufacturing process is provided.