Effect of deep cryogenic treatment on the formation of nano-sized carbides and the wear behavior of D2 tool steel

The effect of deep cryogenic treatment on the microstructure, hardness, and wear behavior of D2 tool steel was studied by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray diffraction （XRD）, hardness test, pin-on-disk wear test, and the reciprocating pin-on-fiat wear test. The results show that deep cryogenic treatment eliminates retained austenite, makes a better carbide distribution, and increases the carbide content. Furthermore, some new nano-sized carbides form during the deep cryogenic treatment, thereby increasing the hardness and improving the wear behavior of the samples.

Effect of deep cryogenic treatment on the properties of 80CrMo12 5 tool steel

The effect of deep cryogenic treatment on the mechanical properties of 80CrMo 12 5 tool steel was investigated. Moreover, the effects of stabilization （holding at room temperature for some periods before deep cryogenic treatment） and tempering before deep cryogenic treatment were studied. The results show that deep cryogenic treatment can eliminate the retained austenite, making a better carbide distribu- tion and a higher carbide amount. As a result, a remarkable improvement in wear resistance of cryogenically treated specimens is observed. Moreover, the ultimate tensile strength increases, and the toughness of the sample decreases. It is also found that both stabilization and tem- pering before deep cryogenic treatment decrease the wear resistance, hardness, and carbides homogeneity compared to the deep cryogeni- cally treated samples. It is concluded that deep cryogenic treatment should be performed without any delay on samples after quenching to reach the highest wear resistance and hardness.

Influence of Deep Cryogenic Treatment (DCT) on Thermo Mechanical Performance of AISI H13 Tool Steel

Deep cryogenic treatment (DCT) is one of the most recent processes being used to treat tool steels. It is a supplementary treatment where components are treated below subzero temperatures for several cryo-soaking hours. This paper focuses on to study the effect of deep cryogenic treatment on Thermo mechanical properties of AISI H-13 tool steel. Deep cryogenic treatment at 32 hours of cryo-soaking time is applied and thermo mechanical performance of tool steel was analyzed by using pin on disk high temperature wear testing and stress rupture testings. The microstructural evolutions during DCT were evaluated by using scanning electron microscope (SEM). It was observed that microstructural modifications like increase in carbide density, fine and uniform martensitic structure during DCT had significantly improved properties.

Novel Pretreatment of Hard Metal Substrate for Better Performance of Diamond Coated Cutting Tools

A surface engineering approach for a novel pre-treatment of hard metal tool substrate for optimum adhesion of diamond coatings is presented. Firsfly, an alkaline solution was used to etch the WC grains to generate a rough surface for better mechanical interlocking. Subsequently, surface Co was removed by etching in acid solution. Then the hard metal substrate was boronized to form a compound interlayer which acted as an efficient diffusion barrier to prevent the outward diffusion of Co. Novel nano-microcrystalline composite diamond film coatings with a very smooth surface was deposited on the surface engineering pre-treated hard metal surface. Promising results of measurement in adhesion strength as well as field cutting tests have been obtained.

The Effect of Heat Treatment Atmosphere on Hardening of Surface Region of H13 Tool Steel

The main objective of the die heat treatment is to enhance the surface hardness and wear properties to extend the die service life. In this paper, a series of heat treatment experiments were conducted under different atmospheric conditions and length of treatment. Four austenitization atmospheric conditions were studied and although each heat treatment condition resulted in a different hardness profile, it did not affect the results for gas nitriding. All samples subjected to the nitriding process produced similar thicknesses of hardened case layer with average hardness of 70 - 72 HRC if the initial carbon content is not too low. It was shown that heat treatment without atmospheric control results in a lower hardness on the surface since the material was subjected to decarburization effect. The stainless steel foil wrapping around the sample and heat treatment in a vacuum furnace could restrict the decarburization process, while pack carburization heat treatment resulted in a carburization effect on the material.

基于刀具寿命的新型螺旋槽丝锥设计

以螺旋槽丝锥参数分析为依据,对M24螺旋槽丝锥的材料选用、表面状态、热处理方法和工艺、刀具结构参数、切削液的选择和刀具寿命进行了研究和优化设计。分析了M24螺旋槽丝锥的热处理工艺参数和金相组织。通过寿命分析发现,研制的丝锥切削扭矩、排屑能力、切屑情况及刀具耐用度与进口丝锥基本相当。本文研究具有一定的应用价值。

肿瘤多学科协作诊疗有效性评价工具研究系统综述

目的了解肿瘤多学科协作诊疗(multidisciplinary diagnosis and treatment,MDT)的有效性评价研究,分析国内外有效性评价工具的发展现状以及差异,为后续肿瘤MDT的总结评价和持续改进、强化MDT监管提供借鉴与参考。方法检索国内外4个文献数据库以获取相关研究文献,并进行文献筛选和系统综述。结果最终纳入文献87篇,中文和英文文献分别为26篇和61篇,发表数量最多的年份是2020年,第一作者所属国家主要为英国。国外评价工具侧重于结构和过程的关键要素,国内评价体系侧重于结果层面的指标内容。结论在国内研究中,MDT评价指标选择的科学性和全面性有待提升,对MDT结构、过程层面的影响因素分析尚需加强,现有评价体系的外推性仍待验证。建议强化评价指标选择的证据支持,重视过程环节的评价,促进对肿瘤MDT影响因素的深入研究,进一步鼓励现有评价体系的实证应用。

急诊自杀未遂病人再自杀风险评估工具的研究进展

对自杀未遂的概念、自杀风险评估工具及临床意义等方面进行综述,以期促进适合我国急诊病人再自杀风险评估工具的开发及使用,为急诊医护人员实施自杀风险评估提供借鉴。

失眠的在线简版行为疗法对失眠障碍的干预效果研究

背景失眠障碍是一种常见的精神疾病,给患者的生活和健康带来严重的负面影响。传统的认知行为疗法(CBT-I)是一种有效的非药物治疗方法,但其操作复杂、耗时长、依从性低等缺点限制了其在真实世界的应用。简版行为疗法(BBT-I)是一种基于CBT-I的简化治疗方法,其疗效与CBT-I相当,更适合在真实世界中推广。然而,BBT-I是否适用于中国失眠障碍人群暂不明确,而通过线上方式进行BBT-I的研究更是缺乏。目的本研究旨在探讨通过微信小程序进行的在线BBT-I(eBBT-I)对中国失眠障碍患者失眠改善的疗效,以及其对患者睡眠信念和态度的影响。方法本研究采用前瞻性非随机对照研究的设计,将2023年2—11月来自暨南大学附属第一医院精神医学科睡眠门诊的失眠障碍患者设为干预组,将线上和线下招募的失眠障碍志愿者设为对照组,干预组接受为期2周的eBBT-I治疗,对照组接受精神卫生教育的伪干预。在干预前后分别测量患者的失眠严重程度指数量表(ISI)和简版睡眠信念与态度问卷(DBAS-16)得分,以评估干预效果。结果研究最终共纳入35例干预组患者和30例对照组患者。主要结局指标:组别与时间对ISI得分存在交互作用(P<0.05);组别与时间分别对ISI得分主效应显著(P<0.05)。干预前3d(基线)两组ISI得分比较,差异无统计学意义(P>0.05);干预后14d干预组ISI得分低于对照组(P<0.05);干预组干预后14 d ISI得分低于组内干预前(P<0.05)。次要结局指标:组别与时间对DBAS-16得分不存在交互作用(P>0.05);时间对DBAS-16得分主效应显著(P<0.05);组别对DBAS-16得分主效应不显著(P>0.05)。干预前3 d(基线)、干预后14 d两组DBAS-16得分比较,差异无统计学意义(P>0.05);干预组干预后14 d DBAS-16得分高于组内干预前(P<0.05)。结论eBBT-I有效地改善了失眠障碍患者的失眠症状和负面影响,但对睡眠信念与态度的改善效果仍有待提升。本研究支持了eBBT-I在中国失眠障碍患者失眠治疗中的可行性和有效性。

躯体痛苦障碍临床诊疗专家共识

躯体痛苦障碍(bodily distress disorder, BDD)是以持续存在躯体症状为特征的精神障碍,患者对躯体症状痛苦体验深刻,但识别、诊断和治疗率偏低。中国医师协会精神科医师分会躯体症状障碍研究组组织成立共识编写专家组,通过系统回顾相关文献,总结已发表的国内外文献,反复讨论制定专家共识。本共识回顾躯体痛苦障碍的概念变迁、流行病学特征、临床特征、诊疗现状以及病程预后,就躯体痛苦障碍的治疗提出较明确的推荐意见,以期为精神科及其他专业同仁规范化诊断和治疗此种疾病提供依据。

维持性血液透析病人治疗负担研究进展

从治疗负担的定义、相关理论、评估工具、影响因素及维持性血液透析病人治疗负担的现状等方面进行综述,以期为今后维持性血液透析病人的慢性病管理提供依据。

电场处理对YG8硬质合金及其刀具性能的影响

为探索一种高效的硬质合金强化处理技术,研究了电场处理对YG8硬质合金显微组织及性能的影响,采用TEM、SEM等对电场处理前后的YG8硬质合金试样及其刀具进行微观组织分析,采用维氏硬度计进行力学性能测试,数控车床进行切削加工实验。结果表明:经电场处理后,YG8硬质合金试样断裂韧性有所增大,其刀具切削性能得到提升,且电场处理刀具的被加工工件表面质量明显得到提高。在脉冲电流作用下,材料会发生电塑性效应,为位错运动提供驱动力,使位错更容易进行增殖和滑移,位错密度增加,从而有利于材料性能的提高。当脉冲电流为15 A/mm^(2)时,断裂韧性达到最大值9.41 MPa·m^(1/2),相比于未使用电场处理的断裂韧性提高了近10%。经电场处理的YG8硬质合金刀具在切削过程中切削温度降低,可有效防止积屑瘤产生,改善切削过程的摩擦状态,保证了切削质量,使得被加工工件表面质量明显提高。

脑卒中患者康复动机的研究进展

从脑卒中患者康复动机概念、测量工具、影响因素(包括社会人口学因素、疾病因素、社会心理因素、康复服务因素)和干预措施方面综述研究进展,以期为开展脑卒中患者康复动机的相关研究提供参考。

螺纹表面处理检测参数研究与应用

螺纹连接是实现零部件组装的主要方法,螺纹连接简单,拆卸方便,已被广泛应用于航空航天、石油化工、5G通信、新能源汽车、兵器和模具等行业。随着科学技术的不断发展,对螺纹连接的要求也日益提高,因而螺纹加工过程中进行监测是质量保证的重要手段。应用螺纹连接的装备产品为保证其长贮要求,会对带有螺纹的零部件进行表面处理,表面处理后螺纹尺寸发生变化,为使用专用螺纹量具完成螺纹加工各阶段的检测。因此,需要进行表面处理前、后螺纹检测参数的研究与应用,以控制表面处理前、后螺纹的加工质量,正确地检测表面处理前、后螺纹尺寸是否合格。

汽车零部件用非调质钢切削性能改进

钢的化学成分、显微组织、力学性能、硫化物形貌等是影响材料切削性能的重要因素。通过碲改质处理可以改善硫化物的形貌,改质后生成的MnTe-MnS共晶化合物可以使硫化物呈椭球体状。结果表明:碲改质后,长宽比小于2的硫化物占比接近50%,90%的硫化物长宽比小于6;碲改质后,材料切削阻抗力降低、刀具磨损量减少、材料表面粗糙度降低,材料的切削性能提高。

甲亢相关房颤的诊疗进展

大量流行病学及临床研究证实显性及亚临床甲亢均与房颤密切相关。高水平甲状腺激素直接作用于心房心肌细胞,通过多层面病理生理学机制介导心房结构、功能及电重构,提高房颤的易感性和可持续性。无论是显性还是亚临床甲亢均能通过治疗逆转,建议尽早筛查甲状腺功能障碍相关心律失常,降低启动抗甲状腺治疗的阈值。目前甲亢合并房颤的管理目标是心率控制和(或)节律控制,防止心力衰竭及脑卒中等并发症。心率控制主要通过抗甲状腺治疗联合β-受体阻滞剂、地尔硫卓和洋地黄等药物实现。大部分患者在甲状腺功能恢复正常后会自发恢复窦性心律,对于未能转律的患者,应在充分抗凝清除左心房血栓后,采取节律控制策略(包括药理学、电转复或导管消融术)。本文主要总结甲亢相关房颤目前循证证据、病理生理机制及治疗进展,为甲状腺疾病相关心律失常防治提供新靶点。

热处理变形控制工艺优化装置设计与研究

热处理工装是保持和提高复杂结构铸件精度的关键技术装备。为消除长度大、壁厚小、型面结构复杂的铸件在机械加工过程中带来的应力,本文结合计算机辅助方法,分析典型零件热处理变形的影响因素,设计和制造热处理工艺优化专用装置。同时,结合实际热处理形变程度,不断完善设计方案。通过测试热处理前后铸件型面变形量的大小,最终确定了适用铸件的热处理变形控制工艺优化装置,极大程度地消除了零件的残余应力,减小了热处理过程中的变形量。

常见工模具钢分类及热处理工艺

工模具钢是模具制造业的基础,它的选择对模具加工行业中的模具设计和制造有着至关重要的作用。工模具钢广泛应用于汽车、航空航天、无线电仪表等行业,且随着模具加工行业的进步和模具钢的大范围应用,研究工模具钢的性能就显得十分重要。热处理工艺是将模具钢应用于实际中的重要一环,合理的热处理工艺可以改善模具钢的强度性能和工艺性能。目前,在试验研究和实际生产领域已有多种热处理工艺,并且研究人员仍在致力于更加高效、更加绿色的新工艺开发。主要概述了一些常见的工模具钢热处理工艺,并对其发展趋势做出展望。

Ion and Gas Nitriding Applied to Steel Tool for Hot Work X38CrMoV5 Nitriding Type: Impact on the Wear Resistance

The present work is to characterize both processes of thermochemical treatments: plasma nitriding and gas. The tests were carried out in collaboration with the Franco-Tunisian heat treatment (F3T) applied to a widely used steel in industrial production as a tool for hot work on X38CrMoV5 (AISI H13). The material underwent a first cycle of hardening heat treatment at 1030℃ followed by two successive incomes at 550℃ and 590℃. After nitriding (ion and gas), the quantification of wear was performed in the laboratory of tribology at SUPMECA (St. Ouen). After defining the test conditions on the alternative tribometer ensuring on one hand a quantitatively sufficient wear and avoiding on the other hand, the phenomenon of jamming. The conditions chosen are: 58.8 N load, frequency 0.5 Hz, friction coefficient μ = 0.5. The wear tracks were scanned using the profilometer Talysurf 5 M type, which allowed us to assess the volume used and the wear rate. Moreover, these tracks were characterized by metallography. What emerges from this work is that the control parameters of ion nitriding ensures a better depth of treatment for the same holding time with a total absence of the white layer known for chipping and fragility.

结直肠癌术后谵妄的诊治研究进展

结直肠癌术后常见的一种并发症为谵妄,其具有较高的发生率,治疗和预防仍然存在挑战。目前国内外对于结直肠癌术后谵妄的相关报道较少,需要开展更深入的诊治研究。本文就结直肠癌术后谵妄的临床特征、发病机制、评估工具、治疗和预防方法等方面进行综述,以促进结直肠癌术后谵妄的早期识别和优化治疗,提高患者的预后和生存质量。