Microstructure and properties of diamond edging wheel made after adding Zn powder to iron-based matrix

The effects of adding Zn powder, different mass fractions of which were 0, 0.7%, 2.1%, 3.5% and 4.9%, on the performances of the iron-based matrix of the diamond edging wheel were studied, namely the hot-pressed sintering structures, the phase compositions and the mechanical properties. On this basis, the properties of three kinds of diamond segments made by adding 0, 2.1%, 3.5% mass fraction of Zn powder and the diamond with a concentration of 24% in iron-based matrix, and the grinding performances of the corresponding three kinds of diamond edging wheels were studied. The results show that with the same sintering process, the area and the morphology of white, dark gray and gray structures in the iron-based matrix with and without Zn powder are obviously changed. The addition of Zn powder with mass fraction of 2.1% is helpful to the diffusion of some substances in the matrix, and the new phase Cu_0.61Zn_0.39 appears in addition to the phases of γ-Fe, (Cu, Sn), and (γ-Fe,Ni), Cu₄₁Sn₁₁ solid solutions, as well as Fe₄Cu₃ and Ni₄Sn intermetallic compounds. With the increase of Zn powder mass fraction, the relative density, the hardness and the wear of the iron-based matrix decrease, but the decline are not obvious. The bending strength of the iron-based matrix increases first and then decreases compared with that without Zn powder, and increases by 16.1% when the mass fraction of Zn powder is 2.1%, reaching the maximum value of 983.2 MPa. However, if the mass fraction of Zn powder is too high, the loss of material will appear when the matrix is hot pressed. After adding diamond to the iron-based matrix with or without Zn powder, the bending strengths of the fabricated segments decrease compared with that without diamond, but the decrease of the matrix with Zn powder are small and the holding force coefficients are larger, which indirectly indicate that the holding forces of the matrix to diamond are higher. When the diamond edging wheel made of iron-based matrix with 2.1% mass fraction of Zn powder is used to grind the edge of infiltrated ceramic brick, compared with the edging wheel made of no Zn powder and 3.5% mass fraction of Zn powder, its sharpness is moderate and its service life is the longest.