Zhi Yuan Wu

Investigation of the Tribological Properties of Si3N4 Ceramic Pair Lubricated by Emulsion of Alkane

A series of experiment were performed to test the tribological properties of Si3N4 ceramic pair lubricated by emulsions of alkane. The experiment results showed that all alkane are very efficient lubricator for Si3N4 ceramic pair. The straight chain alkanes can perform better than branched paraffin or polycyclic saturated hydrocarbon. When added the liquid paraffin with chlorinated paraffin or Oleic acid, the lubrication property become poor. But added with silicone oil emulsion，the lubrication improve further. Base on the molecular structure of reagents, the causative mechanisms is investigated.

Study on the Cutting Process for Remanufacture Deposited Materials

. The systematic experiments for cutting remanufacture deposited materials have been finished. The results show that the deposited materials can be divided into two parts on the view of machining process:surface layer and dense layer. One of the distinctive features on surface layer is impacts to cutting tools in the process. And the process of dense layer cutting is similar with homogeneous material. On the basis of above, the paper puts forward the method which adopts different processing phases for deposited materials.

Study on Effects of Organic Matter Concentrationon Engineering Ceramics Grinding

The grinding liquid concentration has a great influence to its application and cost. Based on the tribological properties, viscosity, heat capacity, the research was conducted to find the performance of grinding fluid with difference concentration. Experimental results show that the grinding fluid can be chosen with low concentration in the process of cutting grinding. For the flat surface grinding and the cylindrical grinding, appropriate method is to give high grinding liquid concentration.

Study on Kaiser Effect of Edge Chipping for Engineering Ceramics during their Failure Process

An edge chipping experiment under static load is adopted to study the Kaiser Effect during the failure process for engineering ceramics. The mechanisms inducing Kaiser Effect are discussed. Some AE signals during the course of Kaiser Effect are analyzed. The results show that there’s obvious Kaiser Effect during the failure process of edge chipping; count, energy and amplitude can be well used to describe the Kaiser Effect. The surface metamorphic layer remained on the ceramic surface during the course of machining is the main factor for Kaiser Effect. Edge distance and mechanics characteristic are the important factors for Kaiser Effect. The study on Kaiser Effect of edge chipping has provided some guidance to prevent edge chipping of engineering ceramics.

Heat Cutting for Remanufacture Hardness Deposited Materials

Three cutting tools, YG610, Si3N4 ceramic tool and CBN were adopted for heat cutting deposited materials. The test results show that though the impacts to the tools reducing, the CBN still break seriously. The condition by Si3N4 ceramic tool is better than CBN, whose types of tool failure change from breakage to wear. The YG610 is best material for heat cutting, whose minimum VB value is only 0.3mm. In the experiment, the wear increase with the increasing of heating temperature, cutting speed, cutting depth. But it decreased with feed rate. The analysis results show that the red-hardness is most importance factor for wears of YG610.

Study on Cutting Hard Thermal Spray Coating

The CBN and YG610 were used for remanufacture thermal spray coating cutting. The feed rates, in the experiment, adopt mode of creep feed. The experiment results showed that the YG610 can cut the thermal spray coating efficiently. And the surface finish qualities are all under Ra1, which can come up to the standard of common grinding. But the CBN tools will be broken in the cutting process, though it can perform well in the evenly qualitative material. By experimental investigation and analyses, it can be conclude that both the high hardness and huge impact exist in cutting process, which are main reasons which induce tools broken. So the materials of tools for cutting thermal spray coating need possess both sufficient hardness and toughness.

Research on Cutting Remanufacture Hardness Deposited Materials in the Impactive Condition

High performance cemented carbide YG610 was adopted for remanufacture hardness deposited materials cutting experiment. The experiment results showed that the same conclusions can be drawn from two group orthogonal experiments. The influence order on cutting capability of cutting tools was: feed rate﹥cutting speed﹥ cutting depth. The cutting length of cutting tools increases monotonously with the feed rate decrease. And the effects by the cutting depth were comparatively small, which is almost negligible in hardness materials cutting. Therefore，low feed rate and large depth of cut are beneficial to keep cutting capability of cutting tools and improve manufacturing productivity. By the results of two orthogonal experiments and extreme deviation analysis, the optimal scheme for cutting parameters were achieved after calculating the best level of the factor.

The Cleaning Mechanisms on Organic Grinding Fluid Applied for Si3N4 Ceramic Grinding

A series of experiment were performed to test the cleaning ability of different organic emulsion for Si3N4 ceramic grinding. The experiment results showed that the grinding fluid made by short chain organic substance and alkane will induces the jam of grinding wheels. At the same time, polar organic substance with long carbon chain can suppress wheel loading phenomenon. The main reason of the jam by alkane is the nonpolar oil film surface possesses the strong attraction to abrasive dust of Si3N4, which will lead to jam in the grinding process. The polar oil film relieves the aggregation of abrasive dust in the grinding area to some extant, which is beneficial to decrease jam. By analyzing the cleaning property by some types of polar organic substances, the paper discusses the relationships of molecular structure characters to their cleaning ability.

Study on the Cutting Mechanism of Remanufacture Deposited Materials in the Impactive Condition

Three cutting tools, YG8, YT15 and YW1, which are different in hardness and toughness, were adopted for deposited materials cutting. From the analysis of test results, it can be known that the toughness is the most importance factor for improving cutting capability when the hardness of deposited materials is low. And with the growth of hardness of workpieces, the hardness of cutting tools plays more and more important roles. When the hardness of deposited materials arrives to HRC56, the hardness of cutting tools becomes the main role for improving cutting capability. On the basis of the results of two orthogonal experiments and extremum deviation analysis, the best scheme for three deposited materials were achieved after obtaining the best level of the factor by computation.

The Blocking Mechanisms and Chemical Modification for Alkane Grinding Fluid Applied for Si3N4 Ceramic Grinding

A series of experiment were performed to test the cleaning ability of different alkane emulsion for Si3N4 ceramic grinding. The experiment results showed that the adsorption film surface of nonpolar alkane have strong attraction to Si3N4 abrasive dust, which will make abrasive dust to gather at the grinding area and finally led to jam. To add alkane grinding fluid with polar organic substances is beneficial to decrease jam. The best additive for anti block is which integrate hydrophobic group and hydrophilic group, both are indispensable.