Comparison of wear performance of diamond tools in frame sawing with different trajectories

In this study, experiments were performed to explore the wear performance of diamond tools with different sawing trajectories in stone processing. The wear morphologies of the diamond segments were analyzed by an optical microscope and scanning electron microscopy. The wear behavior of the diamond segment was investigated comprehensively from the aspects of the wear morphology of matrix and diamond, the remaining height of segments and the height of protrusion of diamond particles. The results indicated that matrix tails are developed behind diamond particles in impacted frame saws guided by the specific eccentric hinge mechanisms. The sawblades can be lifted and cut stone at the maximum horizontal velocity, create many new cutting edges, so that the diamond particles with cutting ability in impacted frame saws are higher than that of the horizontal frame saw. In addition, the hinge mechanisms of impacted frame saws placed in the same direction are conducive to the uniformity of segment wear compared with the hinge mechanisms placed symmetrically. Impact wear is the main wear mechanism of the diamond particles in impacted frame saws, while impact load also accelerates the fracture of diamond particles. Accordingly, the difference of protrusion height between three kinds of frame saws is not particularly large.     

Comparison of wear characteristics of diamond segments under different sawing modes in sawing hard stone

In this study, the wear characteristics of two kinds of diamond segments with different composition of matrix were compared and investigated under two sawing modes through an experiment. Diamond particles were studied through scanning electron microscopy and three dimensional imaging system. Then, the remaining height of diamond segments was measured by digital vernier caliper. The wear characteristics of diamond segments were analyzed from wear morphology, protrusion height of diamond particles and the remaining height of diamond segments. The motion of two sawing modes and their effects on trajectories were analyzed which presented that the rocking reciprocating sawing mode can reduce sawing length and sawing time compared with horizontal reciprocating sawing mode used daily in industry. The results of experiment demonstrated that the main wear mechanism attributed to diamond segments wear is the fracture and falling of diamond particles caused by heavy loads especially in rocking reciprocating sawing mode. The average protrusion height of diamond particles is related with loads and the bonding strength of matrix. However, diamond segments wear can be effectively reduced in rocking reciprocating sawing mode while cobalt-based segments were adopted because a higher bonding strength to diamond particles can be provided compared with iron-based segments. The matrix of segments can be abrased slower while sawing length and sawing time were reduced.     

The effect of operational parameters on diamond tools of frame sawing system: Wear characteristics and optimization in stone processing

A series of sawing experiments was carried out to investigate the effect of operational parameters on the wear characteristics of diamond segment. And the wear mechanism of diamond segment was studied through micro-morphology. The analysis presented that the wear mechanisms of segment metal matrix are mainly attributed to abrasive wear and erosion wear, the wear mechanism of diamond particles mainly includes cleavage fracture caused by the impact load and abrasion caused by scratching. The effect of sawing parameters on the wear rate of segment matrix is consistent with that of diamond particles. The wear resistance of segment matrix increases with the increase of the proportion of diamond particles with micro-fractured and complete crystalline shape, and decreases with the increase of the proportion of diamond particles with macro-fractured and pulled-out. Furthermore, the predicted model was established to evaluate the segment wear per unit by using Design Expert software, and the optimum sawing parameters obtained as a result of the optimization was investigated to provide some guidance for the processing of the enterprise.     

金刚石框架锯锯切研究（Ⅴ）—金刚石结块磨损特征

在对金刚石框架锯锯切加工动力学，锯切破碎机理模型和金刚石框架锯锯切加工石材时的切削力研究的基础上，通过金刚石锯条锯切石材的实验，测量并分析了金刚石结块磨损特征及其分类，金刚石结块磨损机理，金刚石结块磨损与加工时间，进给速度，石材种类，金刚石结块性能和锯条张紧力等因素的关系，提出了加工参数和金刚石结块的优选原则，研究结果为系统开发和改进金刚石工具提供了一个良好的基础，基于 这些结果，可改进结合剂，金刚石质量，金刚石浓度，金刚石粒度，结块尺寸和结块间隔。     

玻璃磨削中电镀金刚石工具的磨损

以镍钴合金为结合剂制备了电镀金刚石工具,对平板玻璃进行了磨边实验,用扫描电子显微镜观察电镀金刚石工具的磨损状态。在玻璃加工过程中,金刚石工具的磨损分为金刚石磨损和结合剂磨损两种情况。金刚石的磨损形式包括：破碎,磨平以及脱落。结合剂的磨损为：在金刚石颗粒的前方形成较深的凹坑,两侧形成较浅的凹坑,金刚石磨粒的后面则形成结合剂的隆起。随着磨削过程的进行,工具的结合剂逐渐被磨除,玻璃磨屑的颜色也相应的由白色向黑色变化。研究结果表明,制备电镀金刚石工具时,电镀结合剂与金刚石磨粒磨损应保持同步,充分发挥金刚石工具的切削作用。     

金刚石框架锯锯切研究(VII)━计算机模拟框架锯锯切过程基础

基于框架锯锯切加工运动学分析、单颗粒和单结块切削力试验结果 ,讨论了采用计算机模拟框架锯锯切过程中所需的运动学、金刚石结块磨损和金刚石颗粒切削力模型 ,以及模拟过程图。采用简化方法计算了金刚石结块表面的理论金刚石颗粒数 ;结合对金刚石结块磨损的研究结果 ,用MontoCarlo方法生成了结块表面的金刚石颗粒的出刃高度、分布位置和磨损形态 ,生成了数字化的金刚石锯条 ,为计算机模拟框架锯锯切加工过程 ,提供了基础数据。     

金属结合剂金刚石工具研究进展

金刚石工具广泛用于天然石材、陶瓷、玻璃、混凝土、硬质合金等的磨削和切割,金属结合剂金刚石工具因具有良好的机械和热学性能而成为金刚石工具的主力军。随着新型陶瓷混凝土等加工对象的不断出现和变化,要求金刚石工具要持续改进,以提高其切削效率、减少自身磨损、同时降低其制造和使用成本。本文综述了人造金刚石颗粒的性能、不同类型金属结合剂的成分组成和基本性能、金刚石与金属结合剂的界面结合状态以及提高其结合强度的措施,并对金属结合剂金刚石工具的发展作了进一步展望。      

Effect of removing internal residual metallic phases on wear resistance of polycrystalline diamond compacts

Internal residual metal phases (mainly cobalt) were effectively removed from polycrystalline diamond compacts (PDCs) by electrolysis to improve their high temperature wear resistance. Through turning granite (dry cutting), we have checked the wear resistance of PDCs with different residual metal removal depth (RMRD). The relationship between the measured wear rate and RMRD was obtained, and the results showed that PDCs treated by electrolysis have a significant improvement in wear resistance. X-ray diffraction (XRD) and scanning electron microscopy (SEM) observation of PDCs' wear surface indicated that diamond–graphite phase transformation occurs for the samples with residual metal phase. The wear mechanism is discussed, and our study suggests that the graphitization is the main wear process of PDCs with internal residual metal phases.     

Ni-P金刚石化学复合镀层制备及摩擦磨损性能分析

目的研究不同粒径微米金刚石对Ni-P金刚石化学复合镀层摩擦磨损性能的影响。方法选择出一组优良的Ni-P化学镀工艺参数,在镀液中分别加入不同粒径的金刚石微粒,制备含不同粒径微米级金刚石颗粒的化学复合镀层。用SEM和XRD,观察并分析了不同粒径金刚石对热处理前后Ni-P金刚石化学复合镀层微观形貌和组织结构的影响;通过硬度和摩擦磨损实验,研究了不同粒径金刚石颗粒对复合镀层硬度及摩擦磨损性能的影响。结果制备的复合镀层厚度为30μm左右,金刚石质量分数达到21%~25%,且金刚石均匀分散在Ni-P镀层中。热处理前镀层为非晶结构,经过400℃×2 h的热处理后,镀层晶化为硬度更高的Ni3P。金刚石能提高镀层硬度,其中粒径为9μm的复合镀层硬度最高,达到1261HV。Ni-P金刚石复合镀层的摩擦系数为0.4~0.52,随着金刚石粒径的增大,摩擦系数不断减小。金刚石使镀层的磨损机制发生了变化,随着金刚石粒径的增大,硬质合金球的磨损加剧。结论随着金刚石粒径的增大,镀层硬度增加,摩擦系数减小,耐磨性增大。     

金刚石粒径及含量对超音速激光沉积金刚石/Cu复合涂层微观结构及性能的影响

目的研究不同金刚石粒径及含量对超音速激光沉积金刚石/Cu复合涂层微观结构及性能的影响。方法利用超音速激光沉积技术制备金刚石/Cu复合涂层。采用扫描电镜和摩擦磨损测试对涂层的显微组织结构和磨损性能进行了分析,用激光闪烁法测量复合涂层的热导率。结果金刚石均匀分布在复合涂层中,原始粉末中金刚石体积分数从30%增加到50%时,复合涂层中金刚石颗粒的面积占比仅从14.01%升至16.79%,远低于金刚石颗粒在原始粉末中的含量。400目金刚石/Cu复合涂层的平均热导率为296 W/(m·K),摩擦系数为0.551;800目金刚石/Cu复合涂层的平均热导率为238 W/(m·K),摩擦系数为0.545。结论原始粉末中金刚石配比的增加并未对复合涂层中金刚石含量的提升有显著作用。金刚石/Cu复合涂层的热导率随着增强相颗粒含量的增加而降低,随着增强相颗粒粒径的增大而提高。不同粒径金刚石颗粒的添加能显著降低Cu涂层的摩擦系数,且小粒径金刚石颗粒的添加使复合涂层的摩擦系数更低和更稳定,从而使其具有更小的磨损量和磨痕宽度,表现出较优的耐磨损性能。     

Wear characteristics of Fe-based diamond composites with cerium oxide (CeO2) reinforcements

To obtain better wear resistance for the metal bond diamond grinding tools, cerium oxide (CeO₂) with different contents were introduced into Fe-based diamond composites. A pin-on-disc wear test was performed to assess the wear properties of the fabricated specimens, and the morphological properties of the worn surface and corresponding wear debris were evaluated to examine the wear mechanism. Results show that the Fe-based diamond composites with CeO₂ addition exhibited an improvement in the densification, mechanical properties and wear resistance. The original long rod-shaped CeO₂ particles converted into the spherical particles <1 μm, dispersing in the Sn phase. The cerium oxide acted as a sintering aid, promoting the diffusion of Fe in the Sn phase during the sintering process. The dominant wear mechanism of the specimen with CeO₂ addition was the adhesive wear, compared with the abrasive wear in the specimen without CeO₂. With the increase in CeO₂ addition amount, the wear rate decreased. But an excessive amount of CeO₂ was detrimental to mechanical and wear performances. The optimal amount of cerium oxide to achieve the best wear resistance was investigated to be 0.8 wt%.     

还原气氛热压烧结技术及其节能减排效益的研究

采用还原气氛带压的钟罩炉烧结(以下简称还原热压烧结)和传统热压烧结两种方式制备金属结合剂试样条和金刚石节块,利用X射线衍射(XRD)、扫描电镜(SEM)、硬度计、电子万能试验机、磨耗比测定仪和氮/氧分析仪等手段,研究两种烧结技术制备的金属结合剂试样条和金刚石节块的微观组织与宏观性能。结果表明,利用两种不同的烧结方式制备的金属结合剂试样条在微观上表现物相结构相同,低熔点Cu-Zn合金组份没与高熔点Fe-Ni合金组份产生冶金结合;在宏观上还原热压烧结制备的金属结合剂试样条的硬度略低于传统热压烧结的,而其抗弯强度和耐磨性均较优。与传统热压烧结工艺相比,还原热压烧结技术在低温低压下既可提高结合剂对金刚石的把持力,又可降低金刚石的热腐蚀。此外,利用还原热压烧结技术能大大降低成本和减少废气的排放。在实际产品应用中,利用还原热压烧结技术制备的φ350 mm金刚石锯片深受国内外客户的好评。     

Wear of PVD Ti/TiN multilayer coatings

The wear characteristics of PVD Ti/TiN multilayer coatings subjected to two-body abrasion and particle erosion have been studied using diamond slurry and silicon carbide particles as abrasive medium and erodant, respectively. The abrasive wear rate of the Ti/TiN multilayer coatings was found to increase with the relative amount of metallic Ti in the coatings. In erosion, the lowest wear rate was recorded for the homogeneous TiN coating. For the Ti/TiN multilayer coatings the erosion rate was found to decrease with an increasing relative amount of metallic Ti in the coatings. It is concluded that the concept of multilayered coatings offers a potent means to tailor the properties of tribological coatings. In particular, demands of different applications can be met by adjusting the relative thickness of metallic Ti in Ti/TiN coatings. The amount of metallic Ti can, for example, be used to control the coating residual stress state. Multilayered Ti/TiN coatings seem promising for combined wear and corrosion protection.     

稀土对金属基金刚石节块力学性能的影响

金属基金刚石工具结合剂中添加少量稀土元素可以细化胎体晶粒,净化金刚石与胎体界面,从而改善结合剂与金刚石的界面结合状态。本研究通过在不同类别金刚石节块中添加或不添加稀土元素,观察其力学性能的变化,并进行比较分析,探讨稀土元素对不同类别金刚石节块力学性能的影响机制。实验结果表明稀土元素对不同类别金刚石节块抗弯强度的影响较为显著,同时,在铜基中加入稀土元素,可以加强金刚石与周围胎体的结合状况,提高胎体对金刚石的把持力。研究成果将有利于促进和推广稀土在金刚石工具制造领域中的应用。     

Wear of a new type of diamond composite

The erosion and abrasion resistances of a new type of composite consisting of diamond particles embedded in a silicon carbide matrix have been evaluated. The investigation is a comparative study in which a conventional cemented carbide, a commercially available polycrystalline diamond material and some common engineering ceramics are included as reference materials. The materials are characterised in terms of wear rates and scanning electron microscopy images of the worn surfaces.

It was found that the new diamond–silicon carbide composites were comparable to the commercial diamond composite, and out-competed the other reference materials in erosive and abrasive wear. The results are discussed in terms of the microstructural characteristics of the composites.     

Co含量对金刚石–WC–Co复合材料耐磨性的影响

随着采矿和城市基建等行业的发展,对矿用WC–Co采掘工具的耐磨性提出了更高的要求。通过添加金刚石增强WC–Co矿用工具的耐磨性是一种可行的新思路。在烧结制备金刚石–WC–Co复合材料的过程中钴相作为催化剂会加速金刚石向石墨转变。为研究Co对复合材料中金刚石石墨化程度的影响,采用放电等离子体烧结技术(SPS)制备金刚石–WC–Co复合材料,分析了复合材料中金刚石石墨化程度并采用砂轮法研究了复合材料的磨损性能和磨损机理。结果表明：金刚石–WC–Co复合材料中金刚石可以起到增韧效果;Co含量增加会促进复合材料致密化进程,同时也会降低复合材料的硬度;随着Co含量增加,复合材料材料耐磨性变差。磨损过程中 WC–Co基体率先被磨损去除,金刚石后被磨损,金刚石会增强材料的耐磨性能。     

Effects of diamond grain characteristics on sawblade wear

One-segmented diamond sawblades containing diamond with varying degrees of etch pits were manufactured to study the wear behaviour of diamond grains during the sawing of granite. The worn surfaces of the diamond segments were analysed by a scanning electron microscope (SEM), and the forces acting on the tool and the wear performance were measured. The results showed that a sawblade containing diamond with a small number of pits during sawing displays predominantly microfractured worn particles on the working segment surface, a lower sawing force, and a better wear performance. When a tool containing a greater number of extensive pits on the diamond grains is used, a higher proportion of macrofracture occurred and wear flats appeared on the worn diamonds. In addition, the sawing forces are relatively higher and the blade performance is poorer.     

基于有限元的20#钢冲蚀磨损行为模拟

目的研究固体颗粒对油气井管柱或地面油气输送管道材料的冲蚀磨损规律。方法通过对石英砂颗粒形状特征抽提了颗粒模型,采用有限元方法模拟了其对20~#钢的冲击磨损动力学行为。在不同冲击角度、不同颗粒粒径和不同冲击速度的条件下,分析材料表面冲击破坏应力特征和材料堆积形态。结果在给定的参数条件下,随着冲击角度的增大,最大等效应力先上升后下降,在40°时达到最大值1370 MPa。高角度冲蚀时,表现为凿坑和塑性挤出;低角度冲蚀时,以微切削和犁沟形唇为主,在冲蚀坑两侧及前端有材料堆积,冲蚀坑前端的变形唇高度逐渐增加,在40°时达到最大值0.019 85 mm。随着冲击速度的增大,最大等效应力单调增大,冲击坑深度变化不大,但冲击粒子前端的堆积材料明显增多,变形唇片高度增大。当粒径小于0.15 mm时,最大等效应力随粒径的增加而增大,粒径为0.15 mm时达到最大值1410 MPa。当粒径超过0.15 mm时,最大等效应力随粒径的增加而减小。随粒径的增加,冲蚀坑深度缓慢增加,粒子前端的变形唇片高度明显增加。结论采用有限元方法对石英砂冲击20~#钢的动力学行为进行了成功的模拟,获得了冲击角度、冲击速度以及颗粒粒径的变化对20~#钢冲击过程中应力分布、冲蚀形貌变化的影响规律。     

Improvement of press dies used for the production of diamond composites by means of DUPLEX-PVD-coatings

In the machining of hard materials such as glass or stone, cemented carbides have been recently replaced by diamond tools, consisting of a metallic carrier, on to which diamond segments are brazed. One of the most economic ways for the production of diamond segments is the cold compaction of the mixture of a metallic powder and diamond particles. Due to a highly abrasive sliding contact between diamond particles and the die walls, the wear rate of the press dies is very high. As a result of a low lifetime of the press dies, they must be replaced in short time periods. To avoid the costly and time-consuming substitution of the press dies, in this work PVD-coatings were deposited on the inner surface of the pre-plasma nitrided press dies (DUPLEX treatment). Thereby, various high and low alloy tool steels were treated by means of plasma nitriding process. Subsequently, a nanocomposite TiAlN coating (nc-TiAlN) was deposited by means of a high ionization magnetron sputtering device on nitrided and non-nitrided steel substrates. The mechanical and tribological properties of these coating systems were studied by means of several standard tests such as nanoindentation, ball-on-disc and scratch test. The most wear resistant coating system was chosen to employ on the inner surface of the press dies. The wear resistance of the press dies developed in this study was tested under real loading condition during compaction of the mixture of diamond particles and cobalt powder. It was revealed that employing plasma nitrided tool, steels coated with nanocomposite TiAlN decreases the wear rate of the press dies up to 76%.     

Simulation,forming process and mechanical property of Cu-Sn-Ti/diamond composites fabricated by selective laser melting

Metal bond diamond abrasive tools with complex structure and high wear efficiency will be widely used in the geological drilling and mechanical processing industries, but are difficult to manufacture by traditional technology. In this paper, selective laser melting (SLM), as one of the additive manufacturing technologies, was used to fabricate Cu-Sn-Ti bonded diamond abrasive composites. Simulations, experiments and characterization were carried out to obtain the appropriate SLM process parameters. Results indicated that the optimal SLM parameters were laser power of 260 W, scanning speed of 300 mm/s and layer thickness of 0.09 mm. Furthermore, the wear resistant performance of SLM sample was compared with hot-pressed sintered sample in terms of mass loss rate, wear morphology and bonding condition. Results showed that diamond particles were seriously pulled-out from hot-pressed sintered sample while this hardly occurred from the wear surface of SLM sample, which was benefited from higher amounts of TiC around the diamond. Consequently, the bonding force to diamond was effectively improved for SLM sample. Therefore, SLM method cannot only fabricated sample with complex structures, but also with better performance. This study provides a novel approach for forming metal bonded diamond tools by SLM in the future.