Abstract: The disclosure provides a gradient structure cubic boron nitride composite sheet and a preparation method thereof. The gradient structure cubic boron nitride composite sheet consists of a cemented carbide substrate, a gradient transition layer, and a CBN layer from bottom to top. The gradient transition layer consists of N gradient layers, and the N is 4 to 18. From bottom to top, there are sequentially a first gradient layer, a second gradient layer, an Nth gradient layer, and so on. Any of the gradient layers consists of CBN and cemented carbide, in which the volume fraction of the cemented carbide in the Nth layer is 5 to 30% less than the volume fraction of the cemented carbide in the N?1th layer, and the volume fraction of the CBN in the Nth layer is 5 to 30% more than the volume fraction of the CBN in the N?1th layer.

Abstract: An oscillating fluidic pressure pulse generator, includes: an outer tube, an upper connector, a lower connector and a vortex fluidic oscillator. A first central fluid channel and a second central fluid channel are respectively formed in the upper connector and the lower connector, two ends of the outer tube are respectively connected to the upper connector and the lower connector through a screw thread, and the vortex fluidic oscillator is provided in the outer tube and abuts against the upper connector and the lower connector; and the vortex fluidic oscillator is provided with an inlet and connected to a fluidic oscillating chamber, two flow guiding blocks are arranged below the fluidic oscillating chamber, a vortex chamber inlet is formed between the two flow guiding blocks, two control channels are respectively formed outside the two flow guiding blocks, a vortex chamber is provided below the vortex chamber inlet.