Multi-Layer Ultra Hard Cutting Elements for Rock Bits
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Solution Overview
Problem
Cutting elements used in rock bits and other cutting tools face challenges with abrasion resistance, strength, and fracture toughness due to thermal mismatch and cracking in ultra hard material layers like polycrystalline diamond and cubic boron nitride, which deteriorate under high temperatures.
Innovation Solution
A cutting element design featuring a substrate with a first ultra hard material layer and a second ultra hard material layer, where the second layer has higher abrasion resistance and a smaller particle size, encapsulating the first layer, and forming a lip with sharp edges as it wears, reducing friction and improving cutting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single ultra hard material layer is used, then the cutting element has simpler structure, but the abrasion resistance and operating life are insufficient
Solution Approach 1:
The cutting element is divided into multiple ultra hard material layers with different properties. The first layer provides a foundation structure, while the second layer with smaller particle size and higher abrasion resistance provides enhanced wear protection. This segmentation allows each layer to perform its specific function, resolving the contradiction between simplicity and abrasion resistance.
Solution Approach 2:
The invention uses composite ultra hard material structures where different ultra hard materials (such as diamond, cubic boron nitride, or their thermally stable products) are combined in layered configurations. This composite approach enables the cutting element to achieve superior abrasion resistance by combining materials with complementary properties, overcoming the limitations of single-material designs.
2Reliability
If larger particle size ultra hard material is used, then the cutting element has higher fracture toughness, but the abrasion resistance decreases
Solution Approach 1:
Different regions of the cutting element are assigned different ultra hard material particle sizes optimized for their specific functions. The second layer has smaller particle size for high abrasion resistance at the cutting interface, while the first layer can have larger particles for fracture toughness. This local optimization resolves the contradiction between abrasion resistance and fracture toughness.
Solution Approach 2:
The invention transitions from considering particle size as a single-dimensional parameter to a multi-dimensional solution by implementing vertical layering. Each layer can have different particle size characteristics, allowing the system to simultaneously achieve high abrasion resistance (small particles in second layer) and fracture toughness (larger particles in first layer) by utilizing the vertical dimension.
3Ease of manufacture
If cobalt binder is used in polycrystalline diamond, then the sintering process is facilitated, but thermal expansion mismatch causes cracking and deterioration
Solution Approach 1:
The invention removes or reduces the cobalt binder content in the ultra hard material layers, particularly in the second layer that is most exposed to thermal conditions. By extracting the problematic cobalt component, the thermal expansion mismatch and associated cracking are eliminated, significantly improving heat resistance while maintaining structural integrity through alternative bonding mechanisms.
Solution Approach 2:
The invention changes the chemical composition parameters of the ultra hard material layers by reducing or eliminating cobalt binder and using alternative binders with thermal expansion coefficients closer to diamond. This parameter change resolves the thermal expansion mismatch issue, allowing the material to withstand high temperatures without cracking while still facilitating the sintering process through controlled composition adjustments.
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 design enhances abrasion resistance, strength, and fracture toughness, reducing thermal mismatch issues and extending the operating life of the cutting layer by forming a lip with sharp edges that provides aggressive cutting while minimizing heat generation and wear.
Implementation Method 1
The process of heating under high pressure is known as sintering
Implementation Method 2
inter-crystalline bonding between the diamond or CBN crystals occurs forming a polycrystalline ultra hard material diamond or CBN layer
Implementation Method 3
Cobalt has a significantly different coefficient of thermal expansion as compared to diamond, and as such, upon heating of the polycrystalline diamond, the cobalt expands, causing cracking to form in the lattice structure
Data Source
AI summary
Cutting elements and bits incorporating such cutting elements are provided. The cutting elements have a substrate, a first ultra hard material layer formed over the substrate, and a second ultra hard material layer formed over the first ultra hard material layer. The second ultra hard material layer has a thickness in the range of 0.05 mm to 2 mm.