PCDM Blank Sintering for Homogeneous Large Diamond Composites
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Solution Overview
Problem
Existing methods for producing polycrystalline diamond blanks are limited by uneven catalyst distribution, resulting in internal stresses and thermal instability, and the inability to produce large-sized blanks due to low raw powder activity, necessitating higher pressure-temperature parameters.
Innovation Solution
A method involving mixing diamond powders of different sizes with aluminum and cobalt powders in a hydrocarbon-based medium, activating the diamond surfaces with low-temperature CCl2F2/O2 plasma, and forming a green blank under HPHT conditions to create a homogeneous polycrystalline composite with a diamond matrix, free of free metal catalysts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If infiltration method is used to introduce catalyst into diamond layer, then catalyst distribution is achieved, but uneven distribution occurs leading to internal stresses and thermal instability
Solution Approach 1:
The catalyst is preliminarily mixed with diamond powder to form a homogeneous green blank before sintering. This preliminary distribution prevents the uneven infiltration that occurs when catalyst is introduced during the sintering process, ensuring uniform catalyst distribution throughout the final polycrystalline diamond product and eliminating internal stresses and thermal instability.
Solution Approach 2:
The invention achieves homogeneous distribution of catalyst particles throughout the diamond powder mixture by thorough mixing in the green blank formation stage. This homogeneity is maintained through the sintering process, resulting in uniform catalyst distribution in the final product, which eliminates the localized concentration variations that cause internal stresses and thermal instability.
2Volume of moving object
If infiltration method is used, then polycrystalline diamond layer is formed, but layer thickness is limited to no more than 3 mm and varies from center to periphery
Solution Approach 1:
The diamond powder and catalyst are preliminarily mixed to form a homogeneous green blank with uniform thickness before sintering. This preliminary preparation ensures that the starting material has consistent dimensions throughout, allowing the sintering process to produce large blanks with uniform layer thickness, overcoming the limitations of infiltration methods that cannot achieve consistent thickness in larger components.
Solution Approach 2:
The invention achieves uniform layer thickness by ensuring homogeneous distribution of diamond powder and catalyst in the green blank before sintering. This initial homogeneity is preserved through the sintering process, enabling production of large blanks with consistent thickness from center to periphery, unlike infiltration methods that produce radial thickness variations.
3Volume of moving object
If higher pressure-temperature parameters are used to produce large-sized blanks, then blank size is increased, but energy consumption and process complexity increase
Solution Approach 1:
The diamond powder and catalyst are preliminarily mixed and compacted into a green blank with optimal density and uniform distribution before sintering. This preliminary preparation ensures that the sintering process proceeds efficiently at lower pressure-temperature parameters, as the pre-positioned catalyst particles are already in contact with diamond grains, eliminating the need for high energy input required by infiltration methods to achieve the same result in large blanks.
Solution Approach 2:
The invention changes the process parameters by using lower pressure and temperature conditions compared to traditional infiltration methods for producing large blanks. The preliminary mixing and uniform distribution of catalyst in the green blank enables efficient sintering at reduced energy input, making the production of large-sized blanks energetically feasible.
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 large-sized blanks with a homogeneous composition and improved mechanical properties, such as enhanced wear resistance, through the formation of diamond-diamond bonds and AlCo intermetallics, without the negative effects of free metal catalysts.
Implementation Method 1
which possesses catalytic activity for the graphite-to-diamond phase transition
Implementation Method 2
sintering the green blank using High-Pressure High-Temperature (HPHT) method
Implementation Method 3
a surface of the diamond powder of the first fraction with particle sizes selected from the range of 5 to 40 μm, and a surface of the diamond powder of the second fraction with particle sizes of 0.05 to 1 μm previously is activated for 1 to 4 hours with a low-temperature CCl 2 F 2 /O 2 plasma
Implementation Method 4
with the addition of the aluminum powder with particle sizes of 0.1 to 3 μm in amount of 2 to 5% by weight of the mixture of the diamond powders, and the cobalt powder with particle sizes of 0.1 to 10 μm in amount of 1 to 15% by weight of the mixture of the diamond powders, as activators for subsequent sintering
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to sintering composite materials based on polycrystalline diamond from a homogeneous, specially prepared mixture of diamond powders with a binder material. The technical problem is to create a possibility to produce a large-sized blank that has homogeneous composition throughout its entire volume, without any free metal catalyst within its structure. A method for producing a large-sized blank made of a polycrystalline composite with a diamond matrix (PCDM) comprises: mixing previously activated with a low-temperature plasma diamond powders in the liquid inert medium, with the addition of aluminum and cobalt powders; evaporating the liquid, forming the green blank and sintering that by the HPHT method up to formation of the large-sized blank made of PCDM which has a homogeneous composition throughout its entire volume.