感应加热金刚石/镍基复合涂层微观组织与性能

采用感应加热的方式,在65Mn钢基体表面制备了金刚石质量分数为10%的复合镍基涂层,利用SEM、EPMA、XRD对钎涂接头的微观组织和相组成进行了分析,研究了感应钎涂中金刚石/钎料界面的元素扩散机制和形成机制。并利用干砂橡胶轮磨损试验机测试了涂层的耐磨性能,分析了金刚石/镍基涂层的耐磨增强机制。结果表明,钎涂层中钎料合金物相主要为Ni₄B₃、(Ni,Fe)固溶体、Ni₃Si₂、CrB;金刚石与钎料合金发生了冶金反应,金刚石/钎料合金界面的C元素分布促使金刚石表面出现了双层碳化物结构,分别为金刚石侧的Cr₃C₂和在Cr₃C₂表面生长的Cr₇C₃。金刚石复合涂层的耐磨性能显著优于钢基体,涂层60min磨损失重仅0.25g,为钢对比试样磨损失重的1/12,金刚石在磨损过程中起到了阻挡犁沟扩展的作用,涂层的失效机制为镍基合金磨损和金刚石的脱落。     

Electrophoretic co-deposition of diamond/borosilicate glass composite coatings

Composite coatings made of diamond powders and borosilicate glass have been deposited on stainless steel substrates by electrophoretic co-deposition. Ethanol and acetone suspensions containing diamond powders of particle size 1-2 μm and borosilicate glass powders of size 0.1-0.5 μm were used. Electrophoretic deposition (EPD) parameters were optimized by a trial-and-error-approach. Microstructures of deposited and sintered coatings were investigated by XRD and SEM analysis. The results show that applied voltages up to 10 V led to thin and incomplete coatings. Voltages higher than 50 V resulted in uneven coatings with uncontrolled thickness and poor uniformity. The best results were achieved using ethanol suspensions. Smooth, uniform and dense coatings with diamond and glass particles distributed uniformly were obtained under applied voltages in the range of 30-50 V and a deposition time of 4 min. The concentration ratio of diamond to borosilicate glass in the composite coatings was in good correlation with the original ratio in suspension, thus control of the coating microstructure and composition is possible. During sintering at 900 °C, the glass particles softened; sintered by viscous flow and spread over the diamond particles surface. Thus a glass layer forms protecting the diamond from oxidization or graphitization and bonding the diamond particles together.     

Sip/ZA40复合材料磨损性能研究

采用磨损试验研究了干磨擦和油润滑摩擦条件下,硅含量对含硅高铝锌基复合材料磨损性能的影响。应用扫描电子显微镜分析了复合材料磨面的形貌特征。结果表明,含硅高铝锌基复合材料的耐磨损性能优于基体合金;在油润滑条件下,硅含量越高,复合材料的耐磨性能越好;在干摩擦条件下,硅含量为4.5％复合材料的耐磨性能优于其它试验材料。含硅材料的磨损机理是微切削磨损、表面脱落和磨粒磨损的综合作用。     

Direct manufacturing of diamond composite coatings onto silicon wafers and heat transfer performance

This paper reveals new insights on how to achieve direct deposition of functional materials onto silicon wafers for cooling purposes. Manufacturing heat spreaders directly onto a microprocessor will negate the need for Thermal Interface Materials (TIMs) which often account for the highest resistances in a typical CPU thermal circuit. In this work we demonstrate that Cold Spray can be tailored to directly print onto a silicon wafer with a layered structure of aluminum, copper and diamond. The thermal performance of the copper/diamond coating was also separately measured using an in-house testing apparatus showing heat-transfer enhancements in agreement with theoretical predictions.     

金刚石/碳化硅/铝复合材料的热膨胀性能

采用气压浸渗法制备金刚石/碳化硅/铝复合材料,研究复合材料的断口形貌以及界面反应,测试复合材料的热膨胀性能。结果表明:金刚石表面Ti镀层使得其选择性粘附不同于未镀钛金刚石的,而在各个面上均粘附有Al,金刚石与基体间有着良好的界面结合,断裂方式以基体断裂为主,其界面反应后,Ti以Al3Ti和Ti-Al-Si等金属间化合物的形式析出,提高金刚石/铝界面的结合强度,降低复合材料的热膨胀系数;随着金刚石颗粒粒径的增大,金刚石和碳化硅颗粒间粒径比的增大增加了整个复合材料的体积分数,从而降低了其热膨胀系数;金刚石颗粒粒径增大导致热膨胀系数升高。这两方面共同影响复合材料的热膨胀系数,但前者起主导作用;金刚石和碳化硅在不同配比下的热膨胀系数随着复合材料中碳化硅含量的增加逐渐增大,Terner模型与Kerner模型的计算平均值能较好地预测实验结果。     

Evolution of thermo-physical properties of diamond/Cu composite materials under thermal shock load

In this paper, the two-flume method was used to study the change laws of the thermal conductivity and thermal expansion coefficient of diamond/Cu composite materials with 100, 300, and 500 cycle numbers, under the action of thermal shock load between-196 and 85 °C; the X-ray diffraction method(XRD) was used to study the change of the residual stress in the thermal shock process of the diamond/Cu composite materials; and the evolution of the fracture microstructure with different thermal shock cycle numbers was observed through scanning electron microscopy(SEM). The results of the study show that the increase of the binder residue at the interface reduces the thermal shock stability of the diamond/Cu composite materials. In addition, under the thermal shock load between-196 and 85 °C, the residual stress of the diamond/Cu composite materials increases continuously with the increase of the cycle numbers, the increase of residual stress leads to a small amount of interface debonding, an increase of the interfacial thermal resistances, and a decrease of the constraints of low-expansion component on material deformation, thus the thermal conductivity decreases slightly and the thermal expansion coefficient increases slightly.     

Wear and cutting performance of diamond composite material-a comparison with tungsten carbide

A series of wear and rock cutting tests were undertaken to assess the wear and cutting performance of a thermally stable diamond composite (TSDC). The wear tests were conducted on a newly designed wear testing rig in which a rotating aluminium oxide grinding wheel is turned (also known as machined) by the testing tool element.The rock cutting tests were performed on a linear rock-cutting planer. The thrust and cutting forces acting on the tool were measured during these tests. A tungsten carbide element was also studied for comparative purposes. The wear coefficients of both materials were used to evaluate wear performance while cutting performance was assessed by tool wear and the rates of increase in forces with cutting distance.     

Development of a micro diamond grinding tool by compound process

This study presents a novel micro-diamond tool which is 100 μm in diameter and that allows precise and micro-grinding during miniature die machining. A novel integrated process technology is proposed that combines “micro-EDM” with “precision composite electroforming” for fabricating micro-diamond tools. First, the metal substrate is cut down to 50 μm in diameter using WEDG, then, the micro-diamonds with 0–2 μm grain is “plated” on the surface of the substrate by composite electroforming, thereby becoming a multilayer micro-grinding tool. The thickness of the electroformed layer is controlled to within 25 μm. The nickel and diamond form the bonder and cutter, respectively. To generate good convection for the electroforming solution, a partition designed with an array of drilled holes is recommended and verified. Besides effectively decreasing the impact energy of the circulatory electroforming solution, the dispersion of the diamond grains and displacement of the nickel ions are noticeably improved. Experimental results indicate that good circularity of the diamond tool can be obtained by arranging the nickel spherules array on the anode. To allow the diamond grains to converge toward the cathode, so as to increase the opportunity of reposing on the substrate, a miniature funnel mold is designed. Then the distribution of the diamond grains on the substrate surface is improved. A micro-ZrO₂ ceramic ferrule is grinded to verify the proposed approach. The surface roughness of R_a = 0.085 μm is obtained. It is demonstrated that the micro-diamond grinding tool with various outer diameters is successfully developed in this study. The suggested approach, which depends on machining applications, can be applied during the final machining. Applications include dental drilling tools, precision optic dies, molds and tools, and biomedical instruments.     

Wear Behavior of CVD-Diamond Tools

Diamond cutting tools are often the only choice for the machining of high-strength and highly abrasive non-ferrous alloys. During machining, a complex interaction of different wear mechanisms takes place on the tools. This interaction considerably hinders a purposeful detection of specific wear mechanisms. Therefore, the objective is to systematically analyze the wear processes that occur when machining a hypereutectic aluminum silicon alloy with CVD-diamond tools. The main wear mechanisms are identified and the limits for the use of various CVD-diamond tools are indicated. The findings gained will serve in the further development of these high-performance cutting materials.     

金刚石/铜复合材料在电子封装材料领域的研究进展

金刚石/铜复合材料作为新型电子封装材料受到了广泛的关注。综述了金刚石/铜复合材料作为电子封装材料的国内外研究现状,介绍了金刚石/铜复合材料的制备工艺,并从材料科学的原理综述了该复合材料主要性能指标（热导率）的影响因素,同时对金刚石/铜复合材料的界面问题进行了分析,最后对金刚石/铜复合材料的未来应用进行了展望。     

Nanoscale surface patterning of diamond utilizing carbon diffusion reaction with a microstructured titanium mold

A novel method was proposed for generating nanoscale surface patterns on single-crystal diamond by carbon diffusion with a microstructured titanium mold under controlled temperature and pressure. The depth, geometry, and surface integrity of the fabricated patterns were investigated by laser micro-Raman spectroscopy and white-light interferometry, and the titanium molds were analyzed by energy dispersive X-ray spectroscopy. The results showed that at specific temperatures and pressures, three-dimensional patterns with a depth of tens of nanometers and sloped/curved walls could be generated on a diamond surface after a few minutes, without causing any surface graphitization. The intensity profile and penetration depth of carbon atoms into the titanium were experimentally measured.     

Form crush dressing of diamond grinding wheels

Form crush dressing is a method to profile diamond grinding wheels. Especially for complex profiles with intricate details and high accuracy an improved form crush profiling system has been developed. The system consists of a hydrostatically supported form crushing disc embedded in a swiveling axis. Form disc wear, which forms a major bottleneck in reaching high accuracy, has been minimized through the development of an advanced wheel synchronization control strategy. Various vitrified grinding wheels and a crushable metal bonded wheel have been tested to show the general applicability of the method to grinding wheels with brittle bond systems.     

Marble cutting with single point cutting tool and diamond segments

An investigation has been undertaken into the frame sawing with diamond blades. The kinematic behaviour of the frame sawing process is discussed. Under different cutting conditions, cutting and indenting-cutting tests are carried out by single point cutting tools and single diamond segments. The results indicate that the depth of cut per diamond grit increases as the blades move forward. Only a few grits per segment can remove the material in the cutting process. When the direction of the stroke changes, the cutting forces do not decrease to zero because of the residual plastic deformation beneath the diamond grits. The plastic deformation and fracture chipping of material are the dominant removal processes, which can be explained by the fracture theory of brittle material indentation.     

Fracture in CVD diamond

The fracture behaviour of thick, textured films of chemical-vapour-deposited diamond is discussed with particular emphasis on the influences asserted by the polycrystalline microstructure. Cracking is investigated on two different scales, firstly where it is large in that it traverses many grains and pertains to the fracture of the bulk. The second is where the fractures are localised, resulting from repeated small particle impacts and the mechanisms of material removal at the grain-size-scale are elucidated. The behaviour at this smaller level can be rationalised in terms intermediate to bulk fracture and that observed in single crystal diamond. The effects of grain size, grain boundaries, crystallographic orientation, twinning, internal stresses and pre-existing flaws are discussed. A new value for the fracture toughness is calculated and the gravimetric erosion rate for different surface orientations measured.     

金刚石/铜复合材料与氧化铝陶瓷的Ag-Cu-Ti活性钎焊(英文)

金刚石/铜复合材料具有低膨胀系数和高热导率等优异性能,使其成为一种理想的电子封装材料。采用97%(72Ag-28Cu)-3%Ti活性钎料对金刚石/铜复合材料和氧化铝陶瓷进行钎焊。发现活性钎料在氧化铝陶瓷和金刚石薄膜表面均具有良好的润湿性,在两者表面的平衡润湿角均小于5°。讨论了主要钎焊条件(如钎焊温度和保温时间等)对接头性能的影响。发现钎焊过程中Ti元素聚集在金刚石颗粒的表面形成TiC化合物,且TiC化合物的形貌与钎焊接头的剪切强度具有紧密联系。推测合适的TiC化合物层厚度可改善钎焊接头的剪切强度,而颗粒状的TiC化合物及过厚的TiC化合物层却会损害钎焊接头的性能。获得的最大剪切强度为117MPa。     

铜基体预沉积铜-金刚石复合过渡层金刚石膜的制备与表征（英文）

在铜基体表面电沉积铜-金刚石复合过渡层,采用电镀铜加固突出基体表面的金刚石颗粒,最后利用热丝化学气相沉积(HFCVD)法在复合过渡层上沉积大面积的与基体结合牢固的连续金刚石膜。采用扫描电子显微镜、拉曼光谱和压痕试验对所沉积的金刚石膜的表面形貌、内应力及膜/基结合性能进行研究。结果表明:金刚石膜由粗大的立方八面体颗粒与细小的(111)显露面颗粒组成,细颗粒填充在粗颗粒之间,形成连续的金刚石膜。复合过渡层中的露头金刚石经CVD同质外延生长成粗金刚石颗粒,而铜表面与粗金刚石之间的二面角上的二次形核繁衍长大成细金刚石颗粒。金刚石膜/基结合力的增强主要来源于金刚石膜与基体之间形成镶嵌咬合和较低的膜内应力。     

Development of micro milling tool made of single crystalline diamond for ceramic cutting

In order to machine micro aspheric ceramic molds precisely and efficiently, micro milling tools made of single crystalline diamond (SCD) are developed. Many cutting edges are fabricated 3-dimensionally on the edge of a cylindrical SCD by a laser beam. Flat binderless tungsten carbide mold was cut with the developed tool to evaluate the tool wear rate and its life. Some micro aspheric molds of tungsten carbide were cut with the tool at a rotational speed of 50,000 min⁻¹. The molds were cut in the ductile mode. The form accuracy obtained was about 100 nm P–V and the surface roughness 12 nm R_z.     

新型铜基结合剂金刚石砂轮性能的研究

在铜基结合剂金刚石砂轮的基础上,通过真空热压法制备新型铜基结合剂金刚石砂轮。然后,对其性能进行测定,并结合扫描电子显微镜对其微观结构进行分析。结果表明:新型铜基结合剂金刚石砂轮的抗折强度、冲击强度、洛氏硬度(HRB)以及加工后工件的表面粗糙度Ra分别为463.96 MPa、13.55kJ/m2、98.67HRB和0.87μm;与普通铜基金属结合剂金刚石砂轮相比,新型铜基结合剂金刚石砂轮的抗折强度、冲击强度和洛氏硬度(HRB)分别提高了23.94%、30.81%和3.14%,且加工后工件的表面粗糙度值Ra从1.86μm下降到0.87μm,表面质量得到明显改善;新型铜基金属结合剂金刚石砂轮具有质轻、强度高、硬度大和磨削效果好的特点。     

Micro-electrical discharge machining of polycrystalline diamond using rotary cupronickel electrode

Cupronickel was used as the electrode material to fabricate microstructures on polycrystalline diamond by electrical discharge machining (EDM). The electrodes were shaped into tiny rotary wheels driven by the flow of EDM fluid. Results showed that material removal rate was improved by a factor of five compared to conventional electrode materials. Raman spectroscopy and energy dispersive X-ray spectroscopy indicated that graphitization of diamond and diffusion-based chemical reactions between nickel and diamond dominated the EDM process. Effects of electrode rotation rate and discharge energy on the EDM characteristics were clarified. High form accuracy (∼0.5 μm/1 mm) and low surface roughness (∼0.1 μm Ra) were obtained.     

Magnesium interlayered diamond coating on silicon

Diamond thin films have been deposited using hot filament chemical vapour deposition technique on manually scratched p-Si(1 0 0) substrate, with and without magnesium interlayer. In spite of magnesium melting point being lower (T_m = 649 °C) than the growth temperature of the substrate (T_s  750 °C) used in these experiments, it was found that high quality diamond films could be grown on Mg covered substrate. A liquid substrate is probably generated during the diamond film growth. Raman spectroscopy analysis exhibited only the triply degenerate, zone centre optical phonon peak at 1333 cm⁻¹ indicating that nearly stress free crystallites were present. Broadening of the Raman peak (11.76 cm⁻¹) indicates that some small crystallites also are present. Scanning electron and atomic force microscopy accompanied by X-ray diffraction analysis where used to compare the details of diamond film growth directly on scratched Si(1 0 0) and Mg interlayered scratched Si(1 0 0) substrates.